A diagram is a symbolic representation of

information Information is an Abstraction, abstract concept that refers to something which has the power Communication, to inform. At the most fundamental level, it pertains to the Interpretation (philosophy), interpretation (perhaps Interpretation (log ...

using visualization techniques. Diagrams have been used since prehistoric times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a

three-dimensional In geometry, a three-dimensional space (3D space, 3-space or, rarely, tri-dimensional space) is a mathematical space in which three values (''coordinates'') are required to determine the position (geometry), position of a point (geometry), poi ...

visualization which is then projected onto a two-dimensional surface. The word '' graph'' is sometimes used as a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

for diagram.

Overview

The term "diagram" in its commonly used sense can have a general or specific meaning: * ''visual information device'' : Like the term "

illustration An illustration is a decoration, interpretation, or visual explanation of a text, concept, or process, designed for integration in print and digitally published media, such as posters, flyers, magazines, books, teaching materials, animations, vi ...

", "diagram" is used as a collective term standing for the whole class of technical genres, including graphs, technical drawings and tables. * ''specific kind of visual display'' : This is the genre that shows qualitative data with shapes that are connected by lines, arrows, or other visual links. In science the term is used in both ways. For example, Anderson (1997) stated more generally: "diagrams are pictorial, yet abstract, representations of information, and maps,

line graph In the mathematics, mathematical discipline of graph theory, the line graph of an undirected graph is another graph that represents the adjacencies between edge (graph theory), edges of . is constructed in the following way: for each edge i ...

s, bar charts,

engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

blueprint A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets introduced by Sir John Herschel in 1842. The process allowed rapid and accurate production of an unlimited number ...

s, and

architect An architect is a person who plans, designs, and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...

s' sketches are all examples of diagrams, whereas photographs and video are not".Michael Anderson (1997). "Introduction to Diagrammatic Reasoning", at ''cs.hartford.edu.'' Retrieved 21 July 2008. On the other hand, Lowe (1993) defined diagrams as specifically "abstract graphic portrayals of the subject matter they represent". In the specific sense diagrams and charts contrast with

computer graphics Computer graphics deals with generating images and art with the aid of computers. Computer graphics is a core technology in digital photography, film, video games, digital art, cell phone and computer displays, and many specialized applications. ...

, technical illustrations,

infographics Infographics (a clipped compound of "information" and "graphics") are graphic visual representations of information, data, or knowledge intended to present information quickly and clearly.Doug Newsom and Jim Haynes (2004). ''Public Relations Wri ...

, maps, and

technical drawing Technical drawing, drafting or drawing, is the act and discipline of composing drawings that visually communicate how something functions or is constructed. Technical drawing is essential for communicating ideas in industry and engineering. ...

s, by showing "abstract rather than literal representations of information". The essence of a diagram can be seen as: * a ''form'' of visual formatting devices * a ''display'' that does not show quantitative data (numerical data), but rather relationships and abstract information * with ''building blocks'' such as geometrical shapes connected by lines,

arrow An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers c ...

s, or other visual links. Or in Hall's (1996) words "diagrams are simplified figures, caricatures in a way, intended to convey essential meaning".Bert S. Hall (1996). "The Didactic and the Elegant: Some Thoughts on Scientific and Technological Illustrations in the Middle Ages and Renaissance". in: B. Braigie (ed.) ''Picturing knowledge: historical and philosophical problems concerning the use of art in science''. Toronto: University of Toronto Press. p.9 These simplified figures are often based on a set of rules. The basic shape according to White (1984) can be characterized in terms of "elegance, clarity, ease, pattern, simplicity, and validity". Elegance is basically determined by whether or not the diagram is "the simplest and most fitting solution to a problem".

Diagrammatology

Diagrammatology Diagrammatology is the academic study of diagrams. It studies fundamental role played by the diagram in the communication and creation of knowledge. Diagrammatology is not only an interdisciplinary subject, but pan-historical and Cross-cultural ...

is the academic study of diagrams. Scholars note that while a diagram may look similar to the thing that it represents, this is not necessary. Rather a diagram may only have structural similarity to what it represents, an idea often attributed to

Charles Sanders Peirce Charles Sanders Peirce ( ; September 10, 1839 – April 19, 1914) was an American scientist, mathematician, logician, and philosopher who is sometimes known as "the father of pragmatism". According to philosopher Paul Weiss (philosopher), Paul ...

. Structural similarity can be defined in terms of a mapping between parts of the diagram and parts of what the diagram represents and the properties of this mapping, such as maintaining relations between these parts and facts about these relations. This is related to the concept of

isomorphism In mathematics, an isomorphism is a structure-preserving mapping or morphism between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between the ...

, or

homomorphism In algebra, a homomorphism is a morphism, structure-preserving map (mathematics), map between two algebraic structures of the same type (such as two group (mathematics), groups, two ring (mathematics), rings, or two vector spaces). The word ''homo ...

in mathematics. Sometimes certain geometric properties (such as which points are closer) of the diagram can be mapped to properties of the thing that a diagram represents. On the other hand, the representation of an object in a diagram may be overly specific and properties that are true in the diagram may not be true for the object the diagram represents. A diagram may act as a means of cognitive extension allowing

reasoning Reason is the capacity of consciously applying logic by drawing valid conclusions from new or existing information, with the aim of seeking the truth. It is associated with such characteristically human activities as philosophy, religion, scien ...

to take place on the diagram based on which constraints are similar.

Gallery of diagram types

There are at least the following types of diagrams:

Logical

Logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the study of deductively valid inferences or logical truths. It examines how conclusions follow from premises based on the structure o ...

al or conceptual diagrams, which take a collection of items and relationships between them, and express them by giving each item a 2D position, while the relationships are expressed as connections between the items or overlaps between the items, for example: File:Tree Example.png, tree diagram File:Neural network.svg, Network diagram File:LampFlowchart.svg, Flowchart File:Set intersection.svg, Venn diagram File:Alphagraphen.png, Existential graph

Quantitative

* Quantitative diagrams, which display a relationship between two variables that take either

discrete Discrete may refer to: *Discrete particle or quantum in physics, for example in quantum theory * Discrete device, an electronic component with just one circuit element, either passive or active, other than an integrated circuit * Discrete group, ...

or a continuous range of values; for example: File:Histogram example.svg,

Histogram A histogram is a visual representation of the frequency distribution, distribution of quantitative data. To construct a histogram, the first step is to Data binning, "bin" (or "bucket") the range of values— divide the entire range of values in ...

File:Graphtestone.svg,

Bar graph A bar chart or bar graph is a chart or graph that presents categorical variable, categorical data with rectangular bars with heights or lengths proportional to the values that they represent. The bars can be plotted vertically or horizontally. A ...

File:Zusammensetzung Shampoo.svg,

Pie chart A pie chart (or a circle chart) is a circular Statistical graphics, statistical graphic which is divided into slices to illustrate numerical proportion. In a pie chart, the arc length of each slice (and consequently its central angle and area) ...

File:Hyperbolic Cosine.svg, Function graph File:R-car stopping distances 1920.svg, Scatter plot File:Hanger Diagram.png, Hanger diagram.

Schematic

* Schematics and other types of diagrams, for example: File:Train schedule of Sanin Line, Japan, 1949-09-15, part.png, Time–distance diagram File:Gear pump exploded.svg, Exploded view File:US 2000 census population density map by state.svg, Population density map File:Pioneer plaque.svg, Pioneer plaque File:Automotive diagrams 01 En.png, Three-dimensional diagram Many of these types of diagrams are commonly generated using diagramming software such as Visio and Gliffy. Diagrams may also be classified according to use or purpose, for example, explanatory and/or how to diagrams. Thousands of diagram techniques exist. Some more examples follow:

Specific diagram types

;A * Activity diagram used in UML 6/9 and SysML ;B * Bachman diagram * Booch – used in

software engineering Software engineering is a branch of both computer science and engineering focused on designing, developing, testing, and maintaining Application software, software applications. It involves applying engineering design process, engineering principl ...

* Bow-tie diagram * Block diagram * Business Process Diagram ;C * Carroll diagram *

Cartogram A cartogram (also called a value-area map or an anamorphic map, the latter common among German-speakers) is a thematic map of a set of features (countries, provinces, etc.), in which their geographic size is altered to be Proportionality (math ...

* Catalytic cycle * Computer network diagram *

Chemical equation A chemical equation is the symbolic representation of a chemical reaction in the form of symbols and chemical formulas. The reactant entities are given on the left-hand side and the Product (chemistry), product entities are on the right-hand side ...

* Curly arrow diagram * Category theory diagrams * Cause-and-effect diagram * Chord diagram (disambiguation) *

Circuit diagram A circuit diagram (or: wiring diagram, electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an Electrical network, electrical circuit. A pictorial circuit diagram uses simple images of components, whil ...

* Class diagram – from UML 1/9 * Cobweb diagram * Collaboration diagram – from UML 2.0 * Communication diagram – from UML 2.0 *

Commutative diagram 350px, The commutative diagram used in the proof of the five lemma In mathematics, and especially in category theory, a commutative diagram is a diagram such that all directed paths in the diagram with the same start and endpoints lead to the s ...

* Comparison diagram * Component diagram – from UML 3/9 * Composite structure diagram – from UML 2.0 * Concept map * Constellation diagram * Context diagram * Control flow diagram * Cross functional flowchart ;D * Data model diagram *

Data flow diagram A data-flow diagram is a way of representing a flow of data through a process or a system (usually an information system). The DFD also provides information about the outputs and inputs of each entity and the process itself. A data-flow diagram ha ...

* Data structure diagram *

Dendrogram A dendrogram is a diagram representing a Tree (graph theory), tree graph. This diagrammatic representation is frequently used in different contexts: * in hierarchical clustering, it illustrates the arrangement of the clusters produced by ...

* Dependency diagram * Deployment diagram – from UML 9/9 * Dynkin diagram * Dot and cross diagram * Double bubble map – used in education * Drakon-chart ;E * Entity-relationship diagram (ERD) * Event-driven process chain *

Euler diagram An Euler diagram (, ) is a diagrammatic means of representing Set (mathematics), sets and their relationships. They are particularly useful for explaining complex hierarchies and overlapping definitions. They are similar to another set diagrammi ...

* Eye diagram – a diagram of a received telecommunications signal * Exploded-view drawing * Express-G ;F *

Family tree A family tree, also called a genealogy or a pedigree chart, is a chart representing family relationships in a conventional tree structure. More detailed family trees, used in medicine and social work, are known as genograms. Representations of ...

* Feynman diagram *

Flow chart A flowchart is a type of diagram that represents a workflow or process. A flowchart can also be defined as a diagrammatic representation of an algorithm, a step-by-step approach to solving a task. The flowchart shows the steps as boxes of va ...

* Flow process chart * Flow diagram * Free body diagram ;G *

Gantt chart A Gantt chart is a bar chart that illustrates a schedule (project management), project schedule. It was designed and popularized by Henry Gantt around the years 1910–1915. Modern Gantt charts also show the Dependency (project management), depe ...

– shows the timing of tasks or activities (used in

project management Project management is the process of supervising the work of a Project team, team to achieve all project goals within the given constraints. This information is usually described in project initiation documentation, project documentation, crea ...

) * Grotrian diagram * Goodman diagram – shows the

fatigue Fatigue is a state of tiredness (which is not sleepiness), exhaustion or loss of energy. It is a signs and symptoms, symptom of any of various diseases; it is not a disease in itself. Fatigue (in the medical sense) is sometimes associated wit ...

data (example: for a

wind turbine A wind turbine is a device that wind power, converts the kinetic energy of wind into electrical energy. , hundreds of thousands of list of most powerful wind turbines, large turbines, in installations known as wind farms, were generating over ...

blades) ;H * Hasse diagram * HIPO diagram ;I * Internal block diagram (IBD) used in SysML * IDEF0 * IDEF1 (entity relations) * Interaction overview diagram – from UML * Ishikawa diagram ;J * Jackson diagram * Jones diagram ;K *

Karnaugh map A Karnaugh map (KM or K-map) is a diagram that can be used to simplify a Boolean algebra expression. Maurice Karnaugh introduced the technique in 1953 as a refinement of Edward W. Veitch's 1952 Veitch chart, which itself was a rediscovery of ...

* Kinematic diagram * Knot diagram ;L * Ladder diagram * Levi graph * Line of balance * Link grammar diagram ;M * Message sequence chart * Mind map – used for learning, brainstorming, memory, visual thinking and problem solving * Minkowski spacetime diagram * Molecular orbital diagram * Motion diagram ;N * N2 * Nassi–Shneiderman diagram or structogram – a representation for

structured programming Structured programming is a programming paradigm aimed at improving the clarity, quality, and development time of a computer program by making specific disciplined use of the structured control flow constructs of selection ( if/then/else) and repet ...

* Nomogram * Network diagram ;O * O–C diagram – a diagnostic plot of ''observed'' minus ''predicted'' values over time * Object diagram – from UML 2/9 * Organigram * Onion diagram – also known as "stacked Venn diagram" ;P * Package diagram from UML 4/9 and SysML * Parametric diagram from SysML * PERT * Petri net – shows the structure of a distributed system as a directed

bipartite graph In the mathematics, mathematical field of graph theory, a bipartite graph (or bigraph) is a Graph (discrete mathematics), graph whose vertex (graph theory), vertices can be divided into two disjoint sets, disjoint and Independent set (graph theo ...

with annotations *

Phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...

- represents a

phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...

(evolutionary relationships among groups of organisms) *

Piping and instrumentation diagram A Piping and Instrumentation Diagram (P&ID) is a detailed diagram in the process industry which shows process equipment together with the instrumentation and control devices. It is also called as mechanical flow diagram (MFD). Superordinate to t ...

(P&ID) * Phase diagram used to present solid/liquid/gas information * Plant diagram * Pressure volume diagram used to analyse engines * Pourbaix diagram * Process flow diagram or PFD – used in

chemical engineering Chemical engineering is an engineering field which deals with the study of the operation and design of chemical plants as well as methods of improving production. Chemical engineers develop economical commercial processes to convert raw materials ...

* Program structure diagram ;R * Radar chart * Radial diagram * Requirement diagram Used in SysML * Rich picture * R-diagram * Routing diagram ;S * Sankey diagram – represents material, energy or cost flows with quantity proportional arrows in a process network * Sentence diagram – represents the grammatical structure of a

natural language A natural language or ordinary language is a language that occurs naturally in a human community by a process of use, repetition, and change. It can take different forms, typically either a spoken language or a sign language. Natural languages ...

sentence * Sequence diagram from UML 8/9 and SysML * SDL/GR diagram – specification and description Language. SDL is a

formal language In logic, mathematics, computer science, and linguistics, a formal language is a set of strings whose symbols are taken from a set called "alphabet". The alphabet of a formal language consists of symbols that concatenate into strings (also c ...

used in

computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...

. * Smith chart * Spider chart * Spray diagram * SSADM – structured systems analysis and design methodology (used in

) * Star chart/

Celestial sphere In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, ...

* State diagram are used for state machines in software engineering from UML 7/9 * Swim lane *

Syntax diagram Syntax diagrams (or railroad diagrams) are a way to represent a context-free grammar. They represent a graphical alternative to Backus–Naur form, EBNF, Augmented Backus–Naur form, and other text-based grammars as metalanguages. Early books ...

used in software engineering to represent a

context-free grammar In formal language theory, a context-free grammar (CFG) is a formal grammar whose production rules can be applied to a nonterminal symbol regardless of its context. In particular, in a context-free grammar, each production rule is of the fo ...

* Systems Biology Graphical Notation – a graphical notation used in diagrams of biochemical and cellular processes studied in

systems biology Systems biology is the computational modeling, computational and mathematical analysis and modeling of complex biological systems. It is a biology-based interdisciplinary field of study that focuses on complex interactions within biological system ...

* System context diagram * System structure * Systematic layout planning ;T *Timing diagram:

digital timing diagram A digital timing diagram represents a set of signals in the time domain. A timing diagram can contain many rows, usually one of them being the clock. It is a tool commonly used in digital electronics, hardware debugging, and digital communicatio ...

*Timing diagram: UML 2.0 * TQM Diagram *

Tree structure A tree structure, tree diagram, or tree model is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree, although the chart is gen ...

* Treemap ;U *

UML diagram The Unified Modeling Language (UML) is a general-purpose visual modeling language that is intended to provide a standard way to visualize the design of a system. UML provides a standard notation for many types of diagrams which can be roughly ...

– Unified Modeling Language (used in

) * Use case diagram – from UML 5/9 and SysML ;V * Value stream mapping * Venn diagram * Violin plot * Voronoi diagram ;W * Warnier-Orr * Wedge-dash diagram * Williot diagram ;Y * Yourdon-Coad – see

Edward Yourdon Edward Nash Yourdon (April 30, 1944 – January 20, 2016) was an American software engineer, computer consultant, author and lecturer, and software engineering methodology pioneer. He was one of the lead developers of the structured analysis tec ...

, used in

References

External links

What is Gigamapping
(website provided by the Oslo School of Architecture and Design) {{Authority control Infographics Modeling languages