Computer science is the study of
computation
Computation is any type of arithmetic or non-arithmetic calculation that follows a well-defined model (e.g., an algorithm).
Mechanical or electronic devices (or, historically, people) that perform computations are known as ''computers''. An esp ...
,
automation
Automation describes a wide range of technologies that reduce human intervention in processes, namely by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machines ...
, and
information. Computer science spans theoretical disciplines (such as
algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s,
theory of computation
In theoretical computer science and mathematics, the theory of computation is the branch that deals with what problems can be solved on a model of computation, using an algorithm, how efficiently they can be solved or to what degree (e.g., ...
,
information theory, and automation) to
practical disciplines
Applied science is the use of the scientific method and knowledge obtained via conclusions from the method to attain practical goals. It includes a broad range of disciplines such as engineering and medicine. Applied science is often contrasted ...
(including the design and implementation of
hardware and
software). Computer science is generally considered an area of
academic research
Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness ...
and distinct from
computer programming.
Algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s and
data structures are central to computer science.
The
theory of computation
In theoretical computer science and mathematics, the theory of computation is the branch that deals with what problems can be solved on a model of computation, using an algorithm, how efficiently they can be solved or to what degree (e.g., ...
concerns abstract
models of computation
In computer science, and more specifically in computability theory and computational complexity theory, a model of computation is a model which describes how an output of a mathematical function is computed given an input. A model describes how ...
and general classes of
problems
A problem is a difficulty which may be resolved by problem solving.
Problem(s) or The Problem may also refer to:
People
* Problem (rapper), (born 1985) American rapper Books
* ''Problems'' (Aristotle), an Aristotelian (or pseudo-Aristotelian) c ...
that can be solved using them. The fields of
cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...
and
computer security involve studying the means for secure communication and for preventing
security vulnerabilities
Vulnerabilities are flaws in a computer system that weaken the overall security of the device/system. Vulnerabilities can be weaknesses in either the hardware itself, or the software that runs on the hardware. Vulnerabilities can be exploited by ...
.
Computer graphics and
computational geometry
Computational geometry is a branch of computer science devoted to the study of algorithms which can be stated in terms of geometry. Some purely geometrical problems arise out of the study of computational geometric algorithms, and such problems a ...
address the generation of images.
Programming language theory
Programming language theory (PLT) is a branch of computer science that deals with the design, implementation, analysis, characterization, and classification of formal languages known as programming languages. Programming language theory is clos ...
considers different ways to describe computational processes, and
database theory concerns the management of repositories of data.
Human–computer interaction investigates the interfaces through which humans and computers interact, and
software engineering focuses on the design and principles behind developing software. Areas such as
operating systems,
network
Network, networking and networked may refer to:
Science and technology
* Network theory, the study of graphs as a representation of relations between discrete objects
* Network science, an academic field that studies complex networks
Mathematic ...
s and
embedded system
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...
s investigate the principles and design behind
complex system
A complex system is a system composed of many components which may interact with each other. Examples of complex systems are Earth's global climate, organisms, the human brain, infrastructure such as power grid, transportation or communication s ...
s.
Computer architecture describes the construction of computer components and computer-operated equipment.
Artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...
and
machine learning aim to synthesize goal-orientated processes such as problem-solving, decision-making, environmental adaptation,
planning and learning found in humans and animals. Within artificial intelligence,
computer vision
Computer vision is an interdisciplinary scientific field that deals with how computers can gain high-level understanding from digital images or videos. From the perspective of engineering, it seeks to understand and automate tasks that the human ...
aims to understand and process image and video data, while
natural language processing
Natural language processing (NLP) is an interdisciplinary subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to proc ...
aims to understand and process textual and linguistic data.
The fundamental concern of computer science is determining what can and cannot be automated. The
Turing Award
The ACM A. M. Turing Award is an annual prize given by the Association for Computing Machinery (ACM) for contributions of lasting and major technical importance to computer science. It is generally recognized as the highest distinction in comput ...
is generally recognized as the highest distinction in computer science.
History
The earliest foundations of what would become computer science predate the invention of the modern
digital computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These prog ...
. Machines for calculating fixed numerical tasks such as the
abacus
The abacus (''plural'' abaci or abacuses), also called a counting frame, is a calculating tool which has been used since ancient times. It was used in the ancient Near East, Europe, China, and Russia, centuries before the adoption of the H ...
have existed since antiquity, aiding in computations such as multiplication and division.
Algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s for performing computations have existed since antiquity, even before the development of sophisticated computing equipment.
Wilhelm Schickard designed and constructed the first working
mechanical calculator in 1623. In 1673,
Gottfried Leibniz
Gottfried Wilhelm (von) Leibniz . ( – 14 November 1716) was a German polymath active as a mathematician, philosopher, scientist and diplomat. He is one of the most prominent figures in both the history of philosophy and the history of mat ...
demonstrated a digital mechanical calculator, called the
Stepped Reckoner. Leibniz may be considered the first
computer scientist
A computer scientist is a person who is trained in the academic study of computer science.
Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus (a ...
and information theorist, because of various reasons, including the fact that he documented the binary number system. In 1820,
Thomas de Colmar launched the
mechanical calculator industry
[In 1851] when he invented his simplified
arithmometer
The arithmometer (french: arithmomètre) was the first digital mechanical calculator strong enough and reliable enough to be used daily in an office environment. This calculator could add and subtract two numbers directly and could perform long ...
, the first calculating machine strong enough and reliable enough to be used daily in an office environment.
Charles Babbage
Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer.
Babbage is considered ...
started the design of the first ''automatic mechanical calculator'', his
Difference Engine, in 1822, which eventually gave him the idea of the first ''programmable mechanical calculator'', his
Analytical Engine
The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician and computer pioneer Charles Babbage. It was first described in 1837 as the successor to Babbage's difference engine, which was a design ...
. He started developing this machine in 1834, and "in less than two years, he had sketched out many of the
salient features of the modern computer".
"A crucial step was the adoption of a punched card system derived from the
Jacquard loom"
making it infinitely programmable.
["The introduction of punched cards into the new engine was important not only as a more convenient form of control than the drums, or because programs could now be of unlimited extent, and could be stored and repeated without the danger of introducing errors in setting the machine by hand; it was important also because it served to crystallize Babbage's feeling that he had invented something really new, something much more than a sophisticated calculating machine." Bruce Collier, 1970] In 1843, during the translation of a French article on the Analytical Engine,
Ada Lovelace
Augusta Ada King, Countess of Lovelace (''née'' Byron; 10 December 1815 – 27 November 1852) was an English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Ana ...
wrote, in one of the many notes she included, an algorithm to compute the
Bernoulli number
In mathematics, the Bernoulli numbers are a sequence of rational numbers which occur frequently in analysis. The Bernoulli numbers appear in (and can be defined by) the Taylor series expansions of the tangent and hyperbolic tangent functions ...
s, which is considered to be the first published algorithm ever specifically tailored for implementation on a computer. Around 1885,
Herman Hollerith invented the
tabulator, which used
punched card
A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
s to process statistical information; eventually his company became part of
IBM. Following Babbage, although unaware of his earlier work,
Percy Ludgate in 1909 published the 2nd of the only two designs for mechanical analytical engines in history. In 1937, one hundred years after Babbage's impossible dream,
Howard Aiken convinced IBM, which was making all kinds of punched card equipment and was also in the calculator business to develop his giant programmable calculator, the
ASCC/Harvard Mark I, based on Babbage's Analytical Engine, which itself used cards and a central computing unit. When the machine was finished, some hailed it as "Babbage's dream come true".
During the 1940s, with the development of new and more powerful
computing machines such as the
Atanasoff–Berry computer and
ENIAC
ENIAC (; Electronic Numerical Integrator and Computer) was the first programmable, electronic, general-purpose digital computer, completed in 1945. There were other computers that had these features, but the ENIAC had all of them in one pac ...
, the term ''computer'' came to refer to the machines rather than their human predecessors. As it became clear that computers could be used for more than just mathematical calculations, the field of computer science broadened to study
computation
Computation is any type of arithmetic or non-arithmetic calculation that follows a well-defined model (e.g., an algorithm).
Mechanical or electronic devices (or, historically, people) that perform computations are known as ''computers''. An esp ...
in general. In 1945,
IBM founded the
Watson Scientific Computing Laboratory
The Thomas J. Watson Research Center is the headquarters for IBM Research. The center comprises three sites, with its main laboratory in Yorktown Heights, New York, U.S., 38 miles (61 km) north of New York City, Albany, New York and wi ...
at
Columbia University in
New York City. The renovated fraternity house on Manhattan's West Side was IBM's first laboratory devoted to pure science. The lab is the forerunner of IBM's Research Division, which today operates research facilities around the world. Ultimately, the close relationship between IBM and Columbia University was instrumental in the emergence of a new scientific discipline, with Columbia offering one of the first academic-credit courses in computer science in 1946. Computer science began to be established as a distinct academic discipline in the 1950s and early 1960s.
The world's first computer science degree program, the
Cambridge Diploma in Computer Science
Diploma in Computer Science, originally known as the Diploma in Numerical Analysis and Automatic Computing, was a conversion course in computer science offered by the University of Cambridge. It is equivalent to a master's degree in present-day nom ...
, began at the
University of Cambridge Computer Laboratory
A computer lab is a space where computer services are provided to a defined community. These are typically public libraries and academic institutions. Generally, users must follow a certain user policy to retain access to the computers. This us ...
in 1953. The first computer science department in the United States was formed at
Purdue University
Purdue University is a public land-grant research university in West Lafayette, Indiana, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and mon ...
in 1962. Since practical computers became available, many applications of computing have become distinct areas of study in their own rights.
Etymology
Although first proposed in 1956,
the term "computer science" appears in a 1959 article in ''
Communications of the ACM
''Communications of the ACM'' is the monthly journal of the Association for Computing Machinery (ACM). It was established in 1958, with Saul Rosen as its first managing editor. It is sent to all ACM members.
Articles are intended for readers with ...
'',
[
]
in which Louis Fein argues for the creation of a ''Graduate School in Computer Sciences'' analogous to the creation of
Harvard Business School
Harvard Business School (HBS) is the graduate business school of Harvard University, a private research university in Boston, Massachusetts. It is consistently ranked among the top business schools in the world and offers a large full-time MBA p ...
in 1921. Louis justifies the name by arguing that, like
management science, the subject is applied and interdisciplinary in nature, while having the characteristics typical of an academic discipline.
His efforts, and those of others such as
numerical analyst George Forsythe, were rewarded: universities went on to create such departments, starting with Purdue in 1962. Despite its name, a significant amount of computer science does not involve the study of computers themselves. Because of this, several alternative names have been proposed. Certain departments of major universities prefer the term ''computing science'', to emphasize precisely that difference. Danish scientist
Peter Naur
Peter Naur (25 October 1928 – 3 January 2016) was a Danish computer science pioneer and Turing award winner. He is best remembered as a contributor, with John Backus, to the Backus–Naur form (BNF) notation used in describing the syntax for mo ...
suggested the term ''datalogy'', to reflect the fact that the scientific discipline revolves around data and data treatment, while not necessarily involving computers. The first scientific institution to use the term was the Department of Datalogy at the University of Copenhagen, founded in 1969, with Peter Naur being the first professor in datalogy. The term is used mainly in the Scandinavian countries. An alternative term, also proposed by Naur, is
data science; this is now used for a
multi-disciplinary field of data analysis, including statistics and databases.
In the early days of computing, a number of terms for the practitioners of the field of computing were suggested in the ''Communications of the ACM''—''turingineer'', ''turologist'', ''flow-charts-man'', ''applied meta-mathematician'', and ''applied
epistemologist
Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics.
Ep ...
''. Three months later in the same journal, ''comptologist'' was suggested, followed next year by ''hypologist''. The term ''computics'' has also been suggested. In Europe, terms derived from contracted translations of the expression "automatic information" (e.g. "informazione automatica" in Italian) or "information and mathematics" are often used, e.g. ''informatique'' (French), ''Informatik'' (German), ''informatica'' (Italian, Dutch), ''informática'' (Spanish, Portuguese), ''informatika'' (
Slavic languages and
Hungarian) or ''pliroforiki'' (''πληροφορική'', which means informatics) in
Greek. Similar words have also been adopted in the UK (as in the
School of Informatics, University of Edinburgh
The School of Informatics is an academic unit of the University of Edinburgh, in Scotland, responsible for research, teaching, outreach and commercialisation in informatics. It was created in 1998 from the former Department of Artificial Intelli ...
). "In the U.S., however,
informatics is linked with applied computing, or computing in the context of another domain."
A folkloric quotation, often attributed to—but almost certainly not first formulated by—
Edsger Dijkstra, states that "computer science is no more about computers than astronomy is about telescopes."
[See the entry
" Computer science" on Wikiquote for the history of this quotation.] The design and deployment of computers and computer systems is generally considered the province of disciplines other than computer science. For example, the study of computer hardware is usually considered part of
computer engineering
Computer engineering (CoE or CpE) is a branch of electrical engineering and computer science that integrates several fields of computer science and electronic engineering required to develop computer hardware and software. Computer engineers ...
, while the study of commercial
computer system
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These progr ...
s and their deployment is often called information technology or
information systems. However, there has been exchange of ideas between the various computer-related disciplines. Computer science research also often intersects other disciplines, such as
cognitive science,
linguistics,
mathematics,
physics,
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
,
Earth science,
statistics,
philosophy, and
logic.
Computer science is considered by some to have a much closer relationship with mathematics than many scientific disciplines, with some observers saying that computing is a mathematical science.
Early computer science was strongly influenced by the work of mathematicians such as
Kurt Gödel,
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...
,
John von Neumann,
Rózsa Péter and
Alonzo Church
Alonzo Church (June 14, 1903 – August 11, 1995) was an American mathematician, computer scientist, logician, philosopher, professor and editor who made major contributions to mathematical logic and the foundations of theoretical computer scien ...
and there continues to be a useful interchange of ideas between the two fields in areas such as
mathematical logic,
category theory
Category theory is a general theory of mathematical structures and their relations that was introduced by Samuel Eilenberg and Saunders Mac Lane in the middle of the 20th century in their foundational work on algebraic topology. Nowadays, cate ...
,
domain theory, and
algebra
Algebra () is one of the broad areas of mathematics. Roughly speaking, algebra is the study of mathematical symbols and the rules for manipulating these symbols in formulas; it is a unifying thread of almost all of mathematics.
Elementary a ...
.
The relationship between Computer Science and Software Engineering is a contentious issue, which is further muddied by
disputes
Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin ''controversia'', as a composite of ''controversus'' – "turned in an opposite d ...
over what the term "Software Engineering" means, and how computer science is defined.
David Parnas
David Lorge Parnas (born February 10, 1941) is a Canadian early pioneer of software engineering, who developed the concept of information hiding in modular programming, which is an important element of object-oriented programming today. He is a ...
, taking a cue from the relationship between other engineering and science disciplines, has claimed that the principal focus of computer science is studying the properties of computation in general, while the principal focus of software engineering is the design of specific computations to achieve practical goals, making the two separate but complementary disciplines.
The academic, political, and funding aspects of computer science tend to depend on whether a department is formed with a mathematical emphasis or with an engineering emphasis. Computer science departments with a mathematics emphasis and with a numerical orientation consider alignment with
computational science
Computational science, also known as scientific computing or scientific computation (SC), is a field in mathematics that uses advanced computing capabilities to understand and solve complex problems. It is an area of science that spans many dis ...
. Both types of departments tend to make efforts to bridge the field educationally if not across all research.
Philosophy
Epistemology of computer science
Despite the word "science" in its name, there is debate over whether or not computer science is a discipline of science,
mathematics,
or engineering.
Allen Newell
Allen Newell (March 19, 1927 – July 19, 1992) was a researcher in computer science and cognitive psychology at the RAND Corporation and at Carnegie Mellon University’s School of Computer Science, Tepper School of Business, and Departm ...
and
Herbert A. Simon argued in 1975, It has since been argued that computer science can be classified as an empirical science since it makes use of empirical testing to evaluate the
correctness of programs, but a problem remains in defining the laws and theorems of computer science (if any exist) and defining the nature of experiments in computer science.
Proponents of classifying computer science as an engineering discipline argue that the reliability of computational systems is investigated in the same way as bridges in
civil engineering and airplanes in
aerospace engineering
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: aeronautical engineering and astronautical engineering. Avionics engineering is si ...
.
They also argue that while empirical sciences observe what presently exists, computer science observes what is possible to exist and while scientists discover laws from observation, no proper laws have been found in computer science and it is instead concerned with creating phenomena.
Proponents of classifying computer science as a mathematical discipline argue that computer programs are physical realizations of mathematical entities and programs can be
deductively reasoned through mathematical
formal methods
In computer science, formal methods are mathematically rigorous techniques for the specification, development, and verification of software and hardware systems. The use of formal methods for software and hardware design is motivated by the expe ...
.
Computer scientists
Edsger W. Dijkstra and
Tony Hoare regard instructions for computer programs as mathematical sentences and interpret formal semantics for programming languages as mathematical
axiomatic system
In mathematics and logic, an axiomatic system is any set of axioms from which some or all axioms can be used in conjunction to logically derive theorems. A theory is a consistent, relatively-self-contained body of knowledge which usually contai ...
s.
Paradigms of computer science
A number of computer scientists have argued for the distinction of three separate paradigms in computer science.
Peter Wegner argued that those paradigms are science, technology, and mathematics.
Peter Denning's working group argued that they are theory, abstraction (modeling), and design. Amnon H. Eden described them as the "rationalist paradigm" (which treats computer science as a branch of mathematics, which is prevalent in theoretical computer science, and mainly employs
deductive reasoning), the "technocratic paradigm" (which might be found in engineering approaches, most prominently in software engineering), and the "scientific paradigm" (which approaches computer-related artifacts from the empirical perspective of
natural sciences,
identifiable in some branches of
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech re ...
).
Computer science focuses on methods involved in design, specification, programming, verification, implementation and testing of human-made computing systems.
Fields
As a discipline, computer science spans a range of topics from theoretical studies of algorithms and the limits of computation to the practical issues of implementing computing systems in hardware and software.
CSAB, formerly called Computing Sciences Accreditation Board—which is made up of representatives of the
Association for Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membe ...
(ACM), and the
IEEE Computer Society
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operatio ...
(IEEE CS)—identifies four areas that it considers crucial to the discipline of computer science: ''theory of computation'', ''algorithms and data structures'', ''programming methodology and languages'', and ''computer elements and architecture''. In addition to these four areas, CSAB also identifies fields such as software engineering, artificial intelligence, computer networking and communication, database systems, parallel computation, distributed computation, human–computer interaction, computer graphics, operating systems, and numerical and
symbolic computation
In mathematics and computer science, computer algebra, also called symbolic computation or algebraic computation, is a scientific area that refers to the study and development of algorithms and software for manipulating mathematical expression ...
as being important areas of computer science.
Theoretical computer science
''Theoretical Computer Science'' is mathematical and abstract in spirit, but it derives its motivation from the practical and everyday computation. Its aim is to understand the nature of computation and, as a consequence of this understanding, provide more efficient methodologies.
Theory of computation
According to
Peter Denning, the fundamental question underlying computer science is, "What can be automated?"
Theory of computation is focused on answering fundamental questions about what can be computed and what amount of resources are required to perform those computations. In an effort to answer the first question,
computability theory
Computability theory, also known as recursion theory, is a branch of mathematical logic, computer science, and the theory of computation that originated in the 1930s with the study of computable functions and Turing degrees. The field has since ...
examines which computational problems are solvable on various theoretical
models of computation
In computer science, and more specifically in computability theory and computational complexity theory, a model of computation is a model which describes how an output of a mathematical function is computed given an input. A model describes how ...
. The second question is addressed by
computational complexity theory
In theoretical computer science and mathematics, computational complexity theory focuses on classifying computational problems according to their resource usage, and relating these classes to each other. A computational problem is a task solved ...
, which studies the time and space costs associated with different approaches to solving a multitude of computational problems.
The famous
P = NP? problem, one of the
Millennium Prize Problems
The Millennium Prize Problems are seven well-known complex mathematical problems selected by the Clay Mathematics Institute in 2000. The Clay Institute has pledged a US$1 million prize for the first correct solution to each problem. According ...
, is an open problem in the theory of computation.
Information and coding theory
Information theory, closely related to
probability and
statistics, is related to the quantification of information. This was developed by
Claude Shannon
Claude Elwood Shannon (April 30, 1916 – February 24, 2001) was an American mathematician, electrical engineer, and cryptographer known as a "father of information theory".
As a 21-year-old master's degree student at the Massachusetts Insti ...
to find fundamental limits on
signal processing
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as sound, images, and scientific measurements. Signal processing techniques are used to optimize transmissions, d ...
operations such as compressing data and on reliably storing and communicating data.
Coding theory is the study of the properties of
code
In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form, sometimes shortened or secret, for communication through a communication ...
s (systems for converting information from one form to another) and their fitness for a specific application. Codes are used for
data compression,
cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...
,
error detection and correction
In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communi ...
, and more recently also for
network coding. Codes are studied for the purpose of designing efficient and reliable
data transmission methods.
Data structures and algorithms
Data structures and algorithms are the studies of commonly used computational methods and their computational efficiency.
Programming language theory and formal methods
Programming language theory is a branch of computer science that deals with the design, implementation, analysis, characterization, and classification of
programming languages and their individual
features
Feature may refer to:
Computing
* Feature (CAD), could be a hole, pocket, or notch
* Feature (computer vision), could be an edge, corner or blob
* Feature (software design) is an intentional distinguishing characteristic of a software ite ...
. It falls within the discipline of computer science, both depending on and affecting
mathematics, software engineering, and
linguistics. It is an active research area, with numerous dedicated academic journals.
Formal methods are a particular kind of
mathematically based technique for the
specification, development and
verification
Verify or verification may refer to:
General
* Verification and validation, in engineering or quality management systems, is the act of reviewing, inspecting or testing, in order to establish and document that a product, service or system meets ...
of software and
hardware systems. The use of formal methods for software and hardware design is motivated by the expectation that, as in other engineering disciplines, performing appropriate mathematical analysis can contribute to the reliability and robustness of a design. They form an important theoretical underpinning for software engineering, especially where safety or security is involved. Formal methods are a useful adjunct to software testing since they help avoid errors and can also give a framework for testing. For industrial use, tool support is required. However, the high cost of using formal methods means that they are usually only used in the development of high-integrity and
life-critical systems, where safety or
security
Security is protection from, or resilience against, potential harm (or other unwanted coercive change) caused by others, by restraining the freedom of others to act. Beneficiaries (technically referents) of security may be of persons and social ...
is of utmost importance. Formal methods are best described as the application of a fairly broad variety of
theoretical computer science
computer science (TCS) is a subset of general computer science and mathematics that focuses on mathematical aspects of computer science such as the theory of computation, lambda calculus, and type theory.
It is difficult to circumscribe the ...
fundamentals, in particular
logic calculi,
formal languages,
automata theory
Automata theory is the study of abstract machines and automata, as well as the computational problems that can be solved using them. It is a theory in theoretical computer science. The word ''automata'' comes from the Greek word αὐτόματ� ...
, and
program semantics, but also
type systems and
algebraic data types
In computer programming, especially functional programming and type theory, an algebraic data type (ADT) is a kind of composite type, i.e., a type formed by combining other types.
Two common classes of algebraic types are product types (i.e., ...
to problems in software and hardware specification and verification.
Computer systems
Computer architecture and organization
Computer architecture, or digital computer organization, is the conceptual design and fundamental operational structure of a computer system. It focuses largely on the way by which the central processing unit performs internally and accesses addresses in memory. Computer engineers study
computational logic
Computational logic is the use of logic to perform or reason about computation. It bears a similar relationship to computer science and engineering as mathematical logic bears to mathematics and as philosophical logic bears to philosophy. It is ...
and design of
computer hardware
Computer hardware includes the physical parts of a computer, such as the case, central processing unit (CPU), random access memory (RAM), monitor, mouse, keyboard, computer data storage, graphics card, sound card, speakers and motherboard.
...
, from individual
processor
Processor may refer to:
Computing Hardware
* Processor (computing)
**Central processing unit (CPU), the hardware within a computer that executes a program
*** Microprocessor, a central processing unit contained on a single integrated circuit (I ...
components,
microcontrollers,
personal computers to
supercomputers and
embedded system
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...
s. The term "architecture" in computer literature can be traced to the work of Lyle R. Johnson and
Frederick P. Brooks, Jr., members of the Machine Organization department in IBM's main research center in 1959.
Concurrent, parallel and distributed computing
Concurrency is a property of systems in which several computations are executing simultaneously, and potentially interacting with each other. A number of mathematical models have been developed for general concurrent computation including
Petri nets,
process calculi
In computer science, the process calculi (or process algebras) are a diverse family of related approaches for formally modelling concurrent systems. Process calculi provide a tool for the high-level description of interactions, communications, and ...
and the
Parallel Random Access Machine model. When multiple computers are connected in a network while using concurrency, this is known as a distributed system. Computers within that distributed system have their own private memory, and information can be exchanged to achieve common goals.
Computer networks
This branch of computer science aims to manage networks between computers worldwide.
Computer security and cryptography
Computer security is a branch of computer technology with the objective of protecting information from unauthorized access, disruption, or modification while maintaining the accessibility and usability of the system for its intended users.
Historical
cryptography
Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...
is the art of writing and deciphering secret messages. Modern cryptography is the scientific study of problems relating to distributed computations that can be attacked. Technologies studied in modern cryptography include symmetric and asymmetric
encryption,
digital signatures,
cryptographic hash function
A cryptographic hash function (CHF) is a hash algorithm (a map of an arbitrary binary string to a binary string with fixed size of n bits) that has special properties desirable for cryptography:
* the probability of a particular n-bit output re ...
s,
key-agreement protocol In cryptography, a key-agreement protocol is a protocol whereby two or more parties can agree on a key in such a way that both influence the outcome. If properly done, this precludes undesired third parties from forcing a key choice on the agreeing ...
s,
blockchain
A blockchain is a type of distributed ledger technology (DLT) that consists of growing lists of records, called ''blocks'', that are securely linked together using cryptography. Each block contains a cryptographic hash of the previous block, ...
,
zero-knowledge proofs, and
garbled circuits.
Databases and data mining
A database is intended to organize, store, and retrieve large amounts of data easily. Digital databases are managed using database management systems to store, create, maintain, and search data, through
database model
A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated. The most popular example of a database model is the relational ...
s and
query language
Query languages, data query languages or database query languages (DQL) are computer languages used to make queries in databases and information systems. A well known example is the Structured Query Language (SQL).
Types
Broadly, query language ...
s. Data mining is a process of discovering patterns in large data sets.
Artificial intelligence
Artificial intelligence (AI) aims to or is required to synthesize goal-orientated processes such as problem-solving, decision-making, environmental adaptation, learning, and communication found in humans and animals. From its origins in
cybernetics
Cybernetics is a wide-ranging field concerned with circular causality, such as feedback, in regulatory and purposive systems. Cybernetics is named after an example of circular causal feedback, that of steering a ship, where the helmsperson ma ...
and in the
Dartmouth Conference (1956), artificial intelligence research has been necessarily cross-disciplinary, drawing on areas of expertise such as
applied mathematics
Applied mathematics is the application of mathematical methods by different fields such as physics, engineering, medicine, biology, finance, business, computer science, and industry. Thus, applied mathematics is a combination of mathematical ...
,
symbolic logic
Mathematical logic is the study of formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory. Research in mathematical logic commonly addresses the mathematical properties of formal sy ...
,
semiotics,
electrical engineering,
philosophy of mind,
neurophysiology
Neurophysiology is a branch of physiology and neuroscience that studies nervous system function rather than nervous system architecture. This area aids in the diagnosis and monitoring of neurological diseases. Historically, it has been dominated ...
, and
social intelligence. AI is associated in the popular mind with
robotic development, but the main field of practical application has been as an embedded component in areas of
software development, which require computational understanding. The starting point in the late 1940s was
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...
's question "Can computers think?", and the question remains effectively unanswered, although the
Turing test is still used to assess computer output on the scale of human intelligence. But the automation of evaluative and predictive tasks has been increasingly successful as a substitute for human monitoring and intervention in domains of computer application involving complex real-world data.
Applied computer science
Computer graphics and visualization
Computer graphics is the study of digital visual contents and involves the synthesis and manipulation of image data. The study is connected to many other fields in computer science, including
computer vision
Computer vision is an interdisciplinary scientific field that deals with how computers can gain high-level understanding from digital images or videos. From the perspective of engineering, it seeks to understand and automate tasks that the human ...
,
image processing
An image is a visual representation of something. It can be two-dimensional, three-dimensional, or somehow otherwise feed into the visual system to convey information. An image can be an artifact, such as a photograph or other two-dimension ...
, and
computational geometry
Computational geometry is a branch of computer science devoted to the study of algorithms which can be stated in terms of geometry. Some purely geometrical problems arise out of the study of computational geometric algorithms, and such problems a ...
, and is heavily applied in the fields of special effects and
video games.
Image and sound processing
Information can take the form of images, sound, video or other multimedia.
Bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented ...
s of information can be streamed via
signals. Its
processing is the central notion of
informatics, the European view on
computing, which studies information processing algorithms independently of the type of information carrier - whether it is electrical, mechanical or biological. This field plays important role in
information theory,
telecommunications,
information engineering
Information engineering is the engineering discipline that deals with the generation, distribution, analysis, and use of information, data, and knowledge in systems. The field first became identifiable in the early 21st century.
The component ...
and has applications in
medical image computing and
speech synthesis, among others. ''What is the lower bound on the complexity of
fast Fourier transform algorithms?'' is one of
unsolved problems in theoretical computer science.
Computational science, finance and engineering
Scientific computing (or
computational science
Computational science, also known as scientific computing or scientific computation (SC), is a field in mathematics that uses advanced computing capabilities to understand and solve complex problems. It is an area of science that spans many dis ...
) is the field of study concerned with constructing
mathematical models
A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in the natural sciences (such as physi ...
and
quantitative analysis techniques and using computers to analyze and solve
scientific
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence f ...
problems. A major usage of scientific computing is
simulation of various processes, including computational
fluid dynamics, physical, electrical, and electronic systems and circuits, as well as societies and social situations (notably war games) along with their habitats, among many others. Modern computers enable optimization of such designs as complete aircraft. Notable in electrical and electronic circuit design are SPICE, as well as software for physical realization of new (or modified) designs. The latter includes essential design software for
integrated circuits.
Social computing and human–computer interaction
Social computing is an area that is concerned with the intersection of social behavior and computational systems. Human–computer interaction research develops theories, principles, and guidelines for user interface designers.
Software engineering
Software engineering is the study of designing, implementing, and modifying the software in order to ensure it is of high quality, affordable, maintainable, and fast to build. It is a systematic approach to software design, involving the application of engineering practices to software. Software engineering deals with the organizing and analyzing of software—it doesn't just deal with the creation or manufacture of new software, but its internal arrangement and maintenance. For example
software testing
Software testing is the act of examining the artifacts and the behavior of the software under test by validation and verification. Software testing can also provide an objective, independent view of the software to allow the business to apprecia ...
,
systems engineering
Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their life cycles. At its core, systems engineering utilizes systems thinking ...
,
technical debt and
software development processes.
Discoveries
The philosopher of computing
Bill Rapaport noted three ''Great Insights of Computer Science'':
*
Gottfried Wilhelm Leibniz's,
George Boole's,
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...
's,
Claude Shannon
Claude Elwood Shannon (April 30, 1916 – February 24, 2001) was an American mathematician, electrical engineer, and cryptographer known as a "father of information theory".
As a 21-year-old master's degree student at the Massachusetts Insti ...
's, and
Samuel Morse's insight: there are only ''two objects'' that a computer has to deal with in order to represent "anything".
:: All the information about any computable problem can be represented using only 0 and 1 (or any other bistable pair that can flip-flop between two easily distinguishable states, such as "on/off", "magnetized/de-magnetized", "high-voltage/low-voltage", etc.).
*
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...
's insight: there are only ''five actions'' that a computer has to perform in order to do "anything".
:: Every algorithm can be expressed in a language for a computer consisting of only five basic instructions:
::* move left one location;
::* move right one location;
::* read symbol at current location;
::* print 0 at current location;
::* print 1 at current location.
*
Corrado Böhm
Corrado Böhm (17 January 1923 – 23 October 2017) was a Professor Emeritus at the University of Rome "La Sapienza" and a computer scientist known especially for his contributions to the theory of structured programming, constructive mathemati ...
and Giuseppe Jacopini's insight: there are only ''three ways of combining'' these actions (into more complex ones) that are needed in order for a computer to do "anything".
:: Only three rules are needed to combine any set of basic instructions into more complex ones:
::*''sequence'': first do this, then do that;
::* '' selection'': IF such-and-such is the case, THEN do this, ELSE do that;
::* ''repetition'': WHILE such-and-such is the case, DO this.
:: Note that the three rules of Boehm's and Jacopini's insight can be further simplified with the use of
goto (which means it is more elementary than
structured programming
Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making extensive use of the structured control flow constructs of selection ( if/then/else) and repetition ( ...
).
Programming paradigms
Programming languages can be used to accomplish different tasks in different ways. Common programming paradigms include:
*
Functional programming, a style of building the structure and elements of computer programs that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It is a declarative programming paradigm, which means programming is done with expressions or declarations instead of statements.
*
Imperative programming
In computer science, imperative programming is a programming paradigm of software that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program ...
, a programming paradigm that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program consists of commands for the computer to perform. Imperative programming focuses on describing how a program operates.
*
Object-oriented programming, a programming paradigm based on the concept of "objects", which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. A feature of objects is that an object's procedures can access and often modify the data fields of the object with which they are associated. Thus object-oriented computer programs are made out of objects that interact with one another.
*
Service-oriented programming, a programming paradigm that uses "services" as the unit of computer work, to design and implement integrated business applications and
mission critical
A mission critical factor of a system is any factor (component, equipment, personnel, process, procedure, software, etc.) that is essential to business operation or to an organization. Failure or disruption of mission critical factors will resul ...
software programs
Many languages offer support for multiple paradigms, making the distinction more a matter of style than of technical capabilities.
Research
Conferences are important events for computer science research. During these conferences, researchers from the public and private sectors present their recent work and meet. Unlike in most other academic fields, in computer science, the prestige of
conference papers is greater than that of journal publications. One proposed explanation for this is the quick development of this relatively new field requires rapid review and distribution of results, a task better handled by conferences than by journals.
Education
Computer Science, known by its near synonyms, Computing, Computer Studies, has been taught in UK schools since the days of
batch processing,
mark sensitive cards and
paper tape
Five- and eight-hole punched paper tape
Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop
Punched tape or perforated paper tape is a form of data storage ...
but usually to a select few students. In 1981, the BBC produced a
micro-computer
A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor. The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (P ...
and
classroom network and Computer Studies became common for GCE
O level
The O-Level (Ordinary Level) is a subject-based qualification conferred as part of the General Certificate of Education. It was introduced in place of the School Certificate in 1951 as part of an educational reform alongside the more in-depth ...
students (11–16-year-old), and Computer Science to
A level
The A-Level (Advanced Level) is a subject-based qualification conferred as part of the General Certificate of Education, as well as a school leaving qualification offered by the educational bodies in the United Kingdom and the educational aut ...
students. Its importance was recognised, and it became a compulsory part of the
National Curriculum, for Key Stage 3 & 4. In September 2014 it became an entitlement for all pupils over the age of 4.
In the
US, with 14,000 school districts deciding the curriculum, provision was fractured. According to a 2010 report by the
Association for Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membe ...
(ACM) and
Computer Science Teachers Association
The Computer Science Teachers Association (CSTA) is a professional association whose mission to “empower, engage and advocate for K-12 CS teachers worldwide.” It supports and encourages education in the field of computer science and related ...
(CSTA), only 14 out of 50 states have adopted significant education standards for high school computer science. According to a 2021 report, only 51% of high schools in the US offer computer science.
Israel, New Zealand, and South Korea have included computer science in their national secondary education curricula, and several others are following.
See also
*
Computer engineering
Computer engineering (CoE or CpE) is a branch of electrical engineering and computer science that integrates several fields of computer science and electronic engineering required to develop computer hardware and software. Computer engineers ...
*
Computer programming
*
Digital Revolution
*
Information and communications technology
*
Information technology
*
List of computer scientists
*
List of computer science awards
This list of computer science awards is an index to articles on notable awards related to computer science. It includes lists of awards by the Association for Computing Machinery, the Institute of Electrical and Electronics Engineers, other comput ...
*
List of important publications in computer science
This is a list of important publications in computer science, organized by field. Some reasons why a particular publication might be regarded as important:
*Topic creator – A publication that created a new topic
*Breakthrough – A pub ...
*
List of pioneers in computer science
This is a list of people who made transformative breakthroughs in the creation, development and imagining of what computers could do.
Pioneers
: ''To arrange the list by date or person (ascending or descending), click that column's small "up-do ...
*
List of unsolved problems in computer science
This article is a list of notable unsolved problems in computer science. A problem in computer science is considered unsolved when no solution is known, or when experts in the field disagree about proposed solutions.
Computational complexity
* ...
*
Programming language
*
Software engineering
Notes
References
Further reading
Overview
*
** "Within more than 70 chapters, every one new or significantly revised, one can find any kind of information and references about computer science one can imagine.
..all in all, there is absolute nothing about Computer Science that can not be found in the 2.5 kilogram-encyclopaedia with its 110 survey articles
.." (Christoph Meinel, ''
Zentralblatt MATH'')
*
** "
..this set is the most unique and possibly the most useful to the
heoretical computer sciencecommunity, in support both of teaching and research
.. The books can be used by anyone wanting simply to gain an understanding of one of these areas, or by someone desiring to be in research in a topic, or by instructors wishing to find timely information on a subject they are teaching outside their major areas of expertise." (Rocky Ross, ''
SIGACT News
ACM SIGACT or SIGACT is the Association for Computing Machinery Special Interest Group on Algorithms and Computation Theory, whose purpose is support of research in theoretical computer science. It was founded in 1968 by Patrick C. Fischer.
Publ ...
'')
*
** "Since 1976, this has been the definitive reference work on computer, computing, and computer science.
..Alphabetically arranged and classified into broad subject areas, the entries cover hardware, computer systems, information and data, software, the mathematics of computing, theory of computation, methodologies, applications, and computing milieu. The editors have done a commendable job of blending historical perspective and practical reference information. The encyclopedia remains essential for most public and academic library reference collections." (Joe Accardin, Northeastern Illinois Univ., Chicago)
*
Selected literature
*
*
*
*
*
** "Covering a period from 1966 to 1993, its interest lies not only in the content of each of these papers – still timely today – but also in their being put together so that ideas expressed at different times complement each other nicely." (N. Bernard, ''Zentralblatt MATH'')
Articles
* Peter J. Denning.
Is computer science science?', Communications of the ACM, April 2005.
* Peter J. Denning,
Great principles in computing curricula', Technical Symposium on Computer Science Education, 2004.
* Research evaluation for computer science, Informatics Europ
report. Shorter journal version: Bertrand Meyer, Christine Choppy, Jan van Leeuwen and Jorgen Staunstrup, ''Research evaluation for computer science'', in
Communications of the ACM
''Communications of the ACM'' is the monthly journal of the Association for Computing Machinery (ACM). It was established in 1958, with Saul Rosen as its first managing editor. It is sent to all ACM members.
Articles are intended for readers with ...
, vol. 52, no. 4, pp. 31–34, April 2009.
Curriculum and classification
*
Association for Computing Machinery
The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a non-profit professional membe ...
1998 ACM Computing Classification System 1998.
* Joint Task Force of Association for Computing Machinery (ACM),
Association for Information Systems
The Association for Information Systems (AIS) is an international, not-for-profit, professional association for scholars of information systems that was established in 1994. The association publishes journals, organizes conferences, and provides ...
(AIS) and
IEEE Computer Society
The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operatio ...
(IEEE CS)
Computing Curricula 2005: The Overview Report September 30, 2005.
*
Norman Gibbs, Allen Tucker. "A model curriculum for a liberal arts degree in computer science". ''Communications of the ACM'', Volume 29 Issue 3, March 1986.
External links
*
Scholarly Societies in Computer Science
What is Computer Science?Photographs of computer scientistsby
Bertrand Meyer
Bertrand Meyer (; ; born 21 November 1950) is a French academic, author, and consultant in the field of computer languages. He created the Eiffel programming language and the idea of design by contract.
Education and academic career
Meyer rece ...
EECS.berkeley.edu
Bibliography and academic search engines
CiteSeer''x''(
article
Article often refers to:
* Article (grammar), a grammatical element used to indicate definiteness or indefiniteness
* Article (publishing), a piece of nonfictional prose that is an independent part of a publication
Article may also refer to:
...
): search engine, digital library and repository for scientific and academic papers with a focus on computer and information science.
DBLP Computer Science Bibliography(
article
Article often refers to:
* Article (grammar), a grammatical element used to indicate definiteness or indefiniteness
* Article (publishing), a piece of nonfictional prose that is an independent part of a publication
Article may also refer to:
...
): computer science bibliography website hosted at Universität Trier, in Germany.
The Collection of Computer Science Bibliographies(
Collection of Computer Science Bibliographies The Collection of Computer Science Bibliographies (founded 1993) is one of the oldest (if not the oldest) bibliography collections freely accessible on the Internet. It is a collection of bibliographies of scientific literature in computer science ...
)
Professional organizations
Association for Computing MachineryIEEE Computer SocietyInformatics EuropeAAAS Computer Science
Misc
Computer Science—Stack Exchange a community-run question-and-answer site for computer science
What is computer science
Is computer science science?Computer Science (Software) Must be Considered as an Independent Discipline.
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