A system is a group of

interacting Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may refer to: Science * Interaction hypothesis, a theory of second language acquisition * Interaction (statistics) * Interactions o ...

or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its

environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...

, is described by its boundaries,

structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

and purpose and expressed in its functioning. Systems are the subjects of study of systems theory and other systems sciences. Systems have several common properties and characteristics, including structure, function(s), behavior and interconnectivity.

Etymology

The term ''system'' comes from the Latin word ''systēma'', in turn from Greek ''systēma'': "whole concept made of several parts or members, system", literary "composition"."σύστημα"
Henry George Liddell, Robert Scott, '' A Greek–English Lexicon'', on Perseus Digits Library.

History

According to

Marshall McLuhan Herbert Marshall McLuhan (July 21, 1911 – December 31, 1980) was a Canadian philosopher whose work is among the cornerstones of the study of media theory. He studied at the University of Manitoba and the University of Cambridge. He began his ...

"System" means "something to look at". You must have a very high visual gradient to have systematization. But in philosophy, prior to Descartes, there was no "system". Plato had no "system". Aristotle had no "system".Marshall McLuhan in: McLuhan: Hot & Cool. Ed. by Gerald Emanuel Stearn. A Signet Book published by The New American Library, New York, 1967, p. 288.

In the 19th century the French physicist

Nicolas Léonard Sadi Carnot ''Sous-lieutenant'' Nicolas Léonard Sadi Carnot (; 1 June 1796 – 24 August 1832) was a French mechanical engineer in the French Army, military scientist and physicist, and often described as the "father of thermodynamics". He published onl ...

, who studied thermodynamics, pioneered the development of the concept of a ''system'' in the

natural science Natural science is one of the branches of science concerned with the description, understanding and prediction of natural phenomena, based on empirical evidence from observation and experimentation. Mechanisms such as peer review and repeatab ...

s. In 1824 he studied the system which he called the ''working substance'' (typically a body of water vapor) in

steam engine A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...

s, in regards to the system's ability to do work when heat is applied to it. The working substance could be put in contact with either a boiler, a cold reservoir (a stream of cold water), or a piston (on which the working body could do work by pushing on it). In 1850, the German physicist Rudolf Clausius generalized this picture to include the concept of the surroundings and began to use the term ''working body'' when referring to the system. The biologist Ludwig von Bertalanffy became one of the pioneers of the general systems theory. In 1945 he introduced ''models, principles, and laws that apply to generalized systems or their subclasses, irrespective of their particular kind, the nature of their component elements, and the relation or 'forces' between them.''1945, ''Zu einer allgemeinen Systemlehre,'' Blätter für deutsche Philosophie, 3/4. (Extract in: Biologia Generalis, 19 (1949), 139–164.

Norbert Wiener Norbert Wiener (November 26, 1894 – March 18, 1964) was an American mathematician and philosopher. He was a professor of mathematics at the Massachusetts Institute of Technology (MIT). A child prodigy, Wiener later became an early researcher i ...

and

Ross Ashby W. Ross Ashby (6 September 1903 – 15 November 1972) was an English psychiatrist and a pioneer in cybernetics, the study of the science of communications and automatic control systems in both machines and living things. His first name was no ...

, who pioneered the use of mathematics to study systems, carried out significant development in the concept of a ''system''. 1948, ''Cybernetics: Or the Control and Communication in the Animal and the Machine.'' Paris, France: Librairie Hermann & Cie, and Cambridge, MA: MIT Press.Cambridge, MA: MIT Press.1956.
An Introduction to Cybernetics
', Chapman & Hall. In the 1980s John Henry Holland, Murray Gell-Mann and others coined the term '' complex adaptive system'' at the interdisciplinary Santa Fe Institute.

Concepts

;Environment and boundaries : Systems theory views the world as a complex system of interconnected parts. One scopes a system by defining its boundary; this means choosing which entities are inside the system and which are outside—part of the

. One can make simplified representations (

models A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure. Models c ...

) of the system in order to understand it and to predict or impact its future behavior. These models may define the structure and behavior of the system. ;Natural and human-made systems :There are natural and human-made (designed) systems. Natural systems may not have an apparent objective but their behavior can be interpreted as purposeful by an observer. Human-made systems are made with various purposes that are achieved by some action performed by or with the system. The parts of a system must be related; they must be "designed to work as a coherent entity" — otherwise they would be two or more distinct systems. OpenSystemRepresentation

;Theoretical framework :Most systems are open systems, exchanging matter and energy with their respective surroundings; like a car, a coffeemaker, or Earth. A closed system exchanges energy, but not matter, with its environment; like a computer or the project

Biosphere 2 Biosphere 2 is an American Earth system science research facility located in Oracle, Arizona. Its mission is to serve as a center for research, outreach, teaching, and lifelong learning about Earth, its living systems, and its place in the univers ...

. An

isolated system In physical science, an isolated system is either of the following: # a physical system so far removed from other systems that it does not interact with them. # a thermodynamic system enclosed by rigid immovable walls through which neither m ...

exchanges neither matter nor energy with its environment. A theoretical example of such system is the Universe. ;Process and transformation process :An open system can also be viewed as a bounded transformation process, that is, a black box that is a process or collection of processes that transform inputs into outputs. Inputs are consumed; outputs are produced. The concept of input and output here is very broad. For example, an output of a passenger ship is the movement of people from departure to destination. ;System model :A system comprises multiple views. Man-made systems may have such views as concept, analysis, design, implementation, deployment, structure, behavior, input data, and output data views. A

system model Systems modeling or system modeling is the interdisciplinary study of the use of models to conceptualize and construct systems in business and IT development.systems architecture, using one single integrated model for the description of multiple views, is a kind of system model.

Subsystem

A subsystem is a set of elements, which is a system itself, and a component of a larger system. The IBM Mainframe ''Job Entry Subsystem'' family (

JES1 Job Entry Subsystem (JES), aka Job Entry Subsystem 1 (JES1), was released by IBM as an integral part of OS/VS1 as an enhancement to the basic functions that users of VS1's predecessor, MFT, had. History IBM proclaimed JES1 to be "the single most i ...

JES2 The Job Entry Subsystem (JES) is a component of IBM's MVS mainframe operating systems that is responsible for managing batch workloads. In modern times, there are two distinct implementations of the Job Entry System called JES2 and JES3. They ar ...

JES3 The Job Entry Subsystem (JES) is a component of IBM's MVS mainframe operating systems that is responsible for managing batch workloads. In modern times, there are two distinct implementations of the Job Entry System called JES2 and JES3. They a ...

, and their HASP/

ASP Asp may refer to: Places * Asp, part of Densbüren, Aargau, Switzerland * Aspe (''Asp'' in Valencian), Alicante, Spain * Asp Lake, a lake in Minnesota Animals * Asp (fish) * Asp (snake), in antiquity, one of several venomous snakes ** ''Cera ...

predecessors) are examples. The main ''elements'' they have in common are the components that handle input, scheduling, spooling and output; they also have the ability to interact with local and remote operators. A subsystem description is a system object that contains information defining the characteristics of an operating environment controlled by the system. The Data tests are performed to verify the correctness of the individual subsystem configuration data (e.g. MA Length, Static Speed Profile, …) and they are related to a single subsystem in order to test its Specific Application (SA).

Analysis

There are many kinds of systems that can be analyzed both

quantitatively Quantitative research is a research strategy that focuses on quantifying the collection and analysis of data. It is formed from a deductive approach where emphasis is placed on the testing of theory, shaped by empiricist and positivist philosop ...

and qualitatively. For example, in an analysis of urban

systems dynamics System dynamics (SD) is an approach to understanding the nonlinear behaviour of complex systems over time using stocks, flows, internal feedback loops, table functions and time delays. Overview System dynamics is a methodology and mathematical ...

, A .W. Steiss defined five intersecting systems, including the physical subsystem and behavioral system. For sociological models influenced by systems theory,

Kenneth D. Bailey Kenneth Dillon Bailey (October 21, 1910 – September 26, 1942) was a United States Marine Corps officer who posthumously received the Medal of Honor for heroic conduct during action during the Battle of Guadalcanal in the Solomon Islands. He ...

defined systems in terms of

conceptual Conceptual may refer to: Philosophy and Humanities *Concept *Conceptualism *Philosophical analysis (Conceptual analysis) *Theoretical definition (Conceptual definition) *Thinking about Consciousness (Conceptual dualism) *Pragmatism (Conceptual pr ...

, concrete, and abstract systems, either

isolated Isolation is the near or complete lack of social contact by an individual. Isolation or isolated may also refer to: Sociology and psychology *Isolation (health care), various measures taken to prevent contagious diseases from being spread **Is ...

closed Closed may refer to: Mathematics * Closure (mathematics), a set, along with operations, for which applying those operations on members always results in a member of the set * Closed set, a set which contains all its limit points * Closed interval, ...

, or open.

Walter F. Buckley Walter Frederick Buckley (April 17, 1921 – January 27, 2006) was an American sociologist, and professor of sociology at the University of New Hampshire. Buckley was among the first to apply concepts from general systems theory based on the work ...

defined systems in sociology in terms of

mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of ...

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

, and process models. Bela H. Banathy cautioned that for any inquiry into a system understanding its kind is crucial, and defined "natural" and "designed", i. e. artificial, systems. It is important not to confuse these abstract definitions. For example, natural systems include subatomic systems, living systems, the Solar System,

galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

, and the Universe, while artificial systems include man-made physical structures, hybrids of natural and artificial systems, and conceptual knowledge. The human elements of organization and functions are emphasized with their relevant abstract systems and representations. Artificial systems inherently have a major defect: they must be premised on one or more fundamental assumptions upon which additional knowledge is built. This is in strict alignment to the

Gödel's incompleteness theorems Gödel's incompleteness theorems are two theorems of mathematical logic Mathematical logic is the study of logic, formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory. Research i ...

. The Artificial system can be defined as a "consistent formalized system which contains elementary arithmetic". These fundamental assumptions are not inherently deleterious, but they must by definition be assumed as true, and if they are actually false then the system is not as structurally integral as is assumed (i.e. it is evident that if the initial expession is false, then the Artificial system is not a "consistent formalized system"). For example, in geometry this is very evident in the postulation of theorems and extrapolation of proofs from them. George J. Klir maintained that no "classification is complete and perfect for all purposes", and defined systems as abstract, real, and

physical systems A physical system is a collection of physical objects. In physics, it is a portion of the physical universe chosen for analysis. Everything outside the system is known as the environment. The environment is ignored except for its effects on the ...

, bounded and

unbounded system Boundedness or bounded may refer to: Economics * Bounded rationality, the idea that human rationality in decision-making is bounded by the available information, the cognitive limitations, and the time available to make the decision * Bounded ...

s, discrete to continuous, pulse to hybrid systems, etc. The interactions between systems and their environments are categorized as relatively closed and open systems. It seems most unlikely that an absolutely closed system can exist or, if it did, that it could be known by man. Important distinctions have also been made between ''hard'' systems – technical in nature and amenable to methods such as

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 enterprise life cycle, life cycles. At its core, systems engineering util ...

, operations research, and quantitative systems analysis – and ''soft'' systems that involve people and organisations, commonly associated with concepts developed by

Peter Checkland Peter Checkland (born 18 December 1930, in Birmingham, UK) is a British management scientist and emeritus professor of systems at Lancaster University. He is the developer of soft systems methodology (SSM): a methodology based on a way of system ...

and

Brian Wilson Brian Douglas Wilson (born June 20, 1942) is an American musician, singer, songwriter, and record producer who co-founded the Beach Boys. Often called a genius for his novel approaches to pop composition, extraordinary musical aptitude, and m ...

through Soft Systems Methodology (SSM) involving methods such as action research and emphasis of participatory designs. Where hard systems might be identified as more "scientific", the distinction between them is often elusive.

Cultural system

A cultural system may be defined as the interaction of different elements of culture. While a cultural system is quite different from a social system, sometimes both together are referred to as a "sociocultural system". A major concern of the social sciences is the problem of order.

Economic system

An economic system is a mechanism (

social institution Institutions are humanly devised structures of rules and norms that shape and constrain individual behavior. All definitions of institutions generally entail that there is a level of persistence and continuity. Laws, rules, social conventions a ...

) which deals with the production,

distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...

and consumption of goods and services in a particular society. The economic system is composed of people,

institutions Institutions are humanly devised structures of rules and norms that shape and constrain individual behavior. All definitions of institutions generally entail that there is a level of persistence and continuity. Laws, rules, social conventions a ...

and their relationships to resources, such as the

convention Convention may refer to: * Convention (norm), a custom or tradition, a standard of presentation or conduct ** Treaty, an agreement in international law * Convention (meeting), meeting of a (usually large) group of individuals and/or companies in a ...

of property. It addresses the problems of economics, like the allocation and scarcity of resources. The international sphere of interacting states is described and analysed in systems terms by several international relations scholars, most notably in the neorealist school. This systems mode of international analysis has however been challenged by other schools of international relations thought, most notably the constructivist school, which argues that an over-large focus on systems and structures can obscure the role of individual agency in social interactions. Systems-based models of international relations also underlies the vision of the international sphere held by the liberal institutionalist school of thought, which places more emphasis on systems generated by rules and interaction governance, particularly economic governance.

Applications

Systems modeling is generally a basic principle in engineering and in social sciences. The system is the representation of the entities under concern. Hence inclusion to or exclusion from system context is dependent on the intention of the modeler. No model of a system will include all features of the real system of concern, and no model of a system must include all entities belonging to a real system of concern.

Information and computer science

In computer science and information science, system is a hardware system, software system, or combination, which has

components Circuit Component may refer to: •Are devices that perform functions when they are connected in a circuit. In engineering, science, and technology Generic systems * System components, an entity with discrete structure, such as an assem ...

as its structure and observable

inter-process communication In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categori ...

s as its behavior. Again, an example will illustrate: There are systems of counting, as with

Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...

, and various systems for filing papers, or catalogues, and various library systems, of which the Dewey Decimal Classification is an example. This still fits with the definition of components which are connected together (in this case to facilitate the flow of information). System can also refer to a framework, aka platform, be it software or hardware, designed to allow software programs to run. A flaw in a component or system can cause the component itself or an entire system to fail to perform its required function, e.g., an incorrect statement or data definition

Engineering and physics

In engineering and physics, a physical system is the portion of the universe that is being studied (of which a thermodynamic system is one major example). Engineering also has the concept of a system referring to all of the parts and interactions between parts of a complex project.

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 enterprise life cycle, life cycles. At its core, systems engineering util ...

is the branch of engineering that studies how this type of system should be planned, designed, implemented, built, and maintained. Expected result is the behavior predicted by the specification, or another source, of the component or system under specified conditions.

Sociology, cognitive science and management research

Social and cognitive sciences recognize systems in human person models and in human societies. They include human brain functions and mental processes as well as normative ethics systems and social/cultural behavioral patterns. In management science, operations research and

organizational development Organization development (OD) is the study and implementation of practices, systems, and techniques that affect organizational change, the goal of which is to modify an organization's performance and/or culture. The organizational changes are ...

(OD), human organizations are viewed as systems (conceptual systems) of interacting components such as subsystems or system aggregates, which are carriers of numerous complex business processes (

organizational behavior Organizational behavior (OB) or organisational behaviour is the: "study of human behavior in organizational settings, the interface between human behavior and the organization, and the organization itself".Moorhead, G., & Griffin, R. W. (1995) ...

s) and organizational structures. Organizational development theorist Peter Senge developed the notion of organizations as systems in his book ''The Fifth Discipline''.

Organizational theorists An organization or organisation (Commonwealth English; see spelling differences), is an entity—such as a company, an institution, or an association—comprising one or more people and having a particular purpose. The word is derived from ...

such as Margaret Wheatley have also described the workings of organizational systems in new metaphoric contexts, such as

quantum physics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ...

chaos theory Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have co ...

, and the self-organization of systems.

Pure logic

There is also such a thing as a

logical system A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system. A form ...

. The most obvious example is the calculus developed simultaneously by Leibniz and Isaac Newton. Another example is George Boole's Boolean operators. Other examples have related specifically to philosophy, biology, or cognitive science.

Maslow's hierarchy of needs Maslow's hierarchy of needs is an idea in psychology proposed by American psychologist Abraham Maslow in his 1943 paper "A Theory of Human Motivation" in the journal ''Psychological Review''. Maslow subsequently extended the idea to include his o ...

applies psychology to biology by using pure logic. Numerous psychologists, including Carl Jung and Sigmund Freud have developed systems which logically organize psychological domains, such as personalities, motivations, or intellect and desire. Often these domains consist of general categories following a

corollary In mathematics and logic, a corollary ( , ) is a theorem of less importance which can be readily deduced from a previous, more notable statement. A corollary could, for instance, be a proposition which is incidentally proved while proving another ...

such as a theorem. Logic has been applied to categories suc