View source for System

{{Short description|Interrelated entities that form a whole}}
{{hatnote group|
{{other uses}}
{{for|the set of rules that govern structure or behavior of people|Social system}}
{{for|the academic field|Systems science}}{{For|the engineering|Systems engineering}}
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{{Use American English|date=September 2023}}
[[File:Diagram Systems.svg|thumb|upright=1.2|Systems can be isolated, closed, or open.]]
A '''system''' is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole.<ref name="merriam-webster-system">{{cite web|url=http://www.merriam-webster.com/dictionary/system|title=Definition of ''system''|website=Merriam-Webster|location=Springfield, MA, USA|access-date=2019-01-16|archive-date=2017-06-05|archive-url=https://web.archive.org/web/20170605222234/https://www.merriam-webster.com/dictionary/system|url-status=live}}</ref> A system, surrounded and influenced by its [[environment (systems)|environment]], is described by its boundaries, [[structure]] and purpose and is expressed in its functioning. Systems are the subjects of study of [[systems theory]] and other [[systems science]]s.

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 language|Greek]] {{lang|grc|σύστημα}} ''systēma'': "whole concept made of several parts or members, system", literary "composition".<ref name=":1">[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dsu%2Fsthma "σύστημα"] {{Webarchive|url=https://web.archive.org/web/20210128131333/http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dsu%2Fsthma |date=2021-01-28 }}, Henry George Liddell, Robert Scott, ''[[A Greek–English Lexicon]]'', on Perseus Digits Library.</ref>

==History==

In the 19th century the French physicist [[Nicolas Léonard Sadi Carnot]], who studied [[thermodynamics]], pioneered the development of the concept of a ''system'' in the [[natural science]]s. In 1824 he studied the system which he called the ''working substance'' (typically a body of water vapor) in [[steam engine]]s, in regard 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 [[environment (systems)|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 [[Systems theory|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.''<ref name="Bertalanfy1945">1945, ''Zu einer allgemeinen Systemlehre,'' Blätter für deutsche Philosophie, 3/4. (Extract in: Biologia Generalis, 19 (1949), 139–164.</ref>

In the late 1940s and mid-50s, 
[[Norbert Wiener]] and [[William Ross Ashby|Ross Ashby]] pioneered the use of mathematics to study systems of control and communication, calling it [[cybernetics]]. <ref name="Wiener1948">
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.</ref><ref name="Ashby1950">1956. ''[http://pespmc1.vub.ac.be/ASHBBOOK.html An Introduction to Cybernetics] {{Webarchive|url=https://web.archive.org/web/20230517080220/http://pespmc1.vub.ac.be/ASHBBOOK.html |date=2023-05-17 }}'', Chapman & Hall.</ref>

In the 1960s [[Marshall McLuhan]] applied general systems theory in an approach that he called a field approach and [[Figure–ground (perception)|figure/ground analysis]], to the study of [[media theory]].<ref>{{cite book |last = McLuhan |first = Marshall
 |author-link=Marshall McLuhan
 |year = 1964
 |title = Understanding Media: The Extensions of Man
 |publisher = McGraw-Hill Education. reissued by Gingko Press, 2003
 |isbn =978-1-58423-073-1}}</ref><ref>{{cite book |last = McLuhan |first = Marshall
 |author-link=Marshall McLuhan
 | author2 =[[Quentin Fiore]]
 |year = 1967
 |title = The Medium Is the Massage: An Inventory of Effects (1st ed.)
 |publisher = Random House. Reissued by Gingko Press, 2001
 |isbn = 978-1-58423-070-0}}</ref>

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 (topology)|boundary]]; this means choosing which entities are inside the system and which are outside—part of the [[environment (systems)|environment]]. One can make simplified representations ([[Scientific modelling|models]]) 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.

[[File:OpenSystemRepresentation.svg|thumb|252px|''Open systems'' have input and output flows, representing exchanges of matter, energy or information with their surroundings.]]

===Theoretical framework===
Most systems are [[Open system (thermodynamics)|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]]. An [[isolated system]] exchanges neither matter nor energy with its environment. A theoretical example of such a system is the [[Universe]].

===Process and transformation process===
An [[open system (systems theory)|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===
{{Main|Systems model}}
A system comprises [[view model|multiple views]]. Human-made systems may have such views as concept, [[systems analysis|analysis]], [[Systems design|design]], [[implementation]], deployment, structure, behavior, input data, and output data views. A [[system model]] is required to describe and represent all these views.

===Systems architecture===
{{Main|Systems architecture}}
A 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]], [[JES2]], [[JES3]], and their [[Houston Automatic Spooling Priority|HASP]]/[[Attached Support Processor|ASP]] 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.<ref>[http://www.ibm.com/support/knowledgecenter/ssw_i5_54/rzaks/rzakssbsd.htm IBM's definition]{{dl|fix-attempted=yes|date=December 2022}}</ref> 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).<ref>{{Cite book|title=European Committee for Electrotechnical Standardization (CENELEC) - EN 50128|publisher=CENELEC|year=2011|location=Brussels, Belgium|pages=Table A.11 – Data Préparation Techniques (8.4)}}</ref>

==Analysis==
There are many kinds of systems that can be analyzed both [[Quantitative research|quantitatively]] and [[Qualitative research|qualitatively]]. For example, in an analysis of urban [[systems dynamics]], A .W. Steiss defined five intersecting systems, including the physical subsystem and behavioral system. For sociological models influenced by systems theory,<ref>Steiss, 1967, pp. 8–18.</ref> [[Kenneth D. Bailey (sociologist)|Kenneth D. Bailey]] defined systems in terms of [[conceptual system|conceptual]], [[Concrete (philosophy)|concrete]], and abstract systems, either [[Isolated system|isolated]], [[Closed system|closed]], or [[Open system (systems theory)|open]].<ref>Bailey, 1994.</ref> [[Walter F. Buckley]] defined systems in sociology in terms of [[Mechanics|mechanical]], [[organic (model)|organic]], and [[process modeling|process models]].<ref>Buckley, 1967.</ref> [[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.<ref>Banathy, 1997.</ref> For example, natural systems include [[subatomic]] systems, [[living systems theory|living systems]], the [[Solar System]], [[Galaxy|galaxies]], 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 with [[Gödel's incompleteness theorems]]. The Artificial system can be defined as a "consistent formalized system which contains elementary arithmetic".<ref>K.Gödel, 1931</ref> 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 expression is false, then the artificial system is not a "consistent formalized system"). For example, in [[geometry]] this is very evident in the postulation of [[theorem]]s 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 [[conceptual system|conceptual]] [[physical systems]], bounded and [[unbounded system]]s, discrete to continuous, pulse to [[hybrid system]]s, etc. The interactions between systems and their environments are categorized as relatively closed and [[open system (systems theory)|open systems]].<ref>Klir, 1969, pp. 69–72</ref> Important distinctions have also been made between ''hard'' systems – technical in nature and amenable to methods such as [[systems engineering]], operations research, and quantitative systems analysis – and ''soft'' systems that involve people and organizations, commonly associated with concepts developed by [[Peter Checkland]] and [[Brian Wilson (systems scientist)|Brian Wilson]] through [[Soft systems methodology|Soft Systems Methodology]] (SSM) involving methods such as [[action research]] and emphasis of participatory designs.<ref>Checkland, 1997; Flood, 1999.</ref> Where hard systems might be identified as more ''scientific'', the distinction between them is often elusive.

===Economic system===
{{Main|Economic system}}

An economic system is a [[social institution]] which deals with the [[Economic production|production]], [[distribution (business)|distribution]] and [[consumption (economics)|consumption]] of [[Good (economics)|goods]] and [[Service (economics)|services]] in a particular [[society]]. The economic system is composed of [[person|people]], [[institutions]] and their relationships to resources, such as the [[Convention (norm)|convention]] of [[property]]. It addresses the problems of [[economics]], like the allocation and scarcity of resources.

The international sphere of interacting states is described and analyzed in systems terms by several international relations scholars, most notably in the [[Neorealism (international relations)|neorealist school]]. This systems mode of international analysis has however been challenged by other schools of international relations thought, most notably the [[Constructivism (international relations)|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 underlie the vision of the international sphere held by the [[Institutional liberalism|liberal institutionalist]] school of thought, which places more emphasis on systems generated by rules and interaction governance, particularly economic governance.

===Information and computer science===
In [[computer science]] and [[information science]], a ''system'' is a hardware system, software system, or combination, which has [[Component (UML)|components]] as its structure and observable [[inter-process communication]]s as its behavior. 

There are systems of counting, as with [[Roman numerals]], and various systems for filing papers, or catalogs, and various library systems, of which the [[Dewey Decimal Classification]] is an example. This still fits with the definition of components that are connected together (in this case to facilitate the flow of information).

System can also refer to a framework, aka [[platform (computing)|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 (computer science)|statement]] or [[Data definition language|data definition]]<ref name=":0">{{Cite web|url=http://glossar.german-testing-board.info/|title=ISTQB Standard glossary of terms used in Software Testing|access-date=15 March 2019|archive-date=5 November 2018|archive-url=https://web.archive.org/web/20181105182224/http://glossar.german-testing-board.info/|url-status=dead}}</ref>

===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]] is the branch of engineering that studies how this type of system should be planned, designed, implemented, built, and maintained.<ref name=":0" />

===Sociology, cognitive science and management research===
Social and [[cognitive science]]s recognize systems in models of individual humans and in human societies. They include human brain functions and mental processes as well as normative ethics systems and social and cultural behavioral patterns.<!--[[User:Kvng/RTH]]-->

In [[management science]], [[operations research]] and [[organizational development]] (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]]s) and organizational structures. Organizational development theorist [[Peter Senge]] developed the notion of organizations as systems in his book ''The Fifth Discipline''.

[[Organizational studies|Organizational theorists]] such as [[Margaret Wheatley]] have also described the workings of organizational systems in new metaphoric contexts, such as [[quantum physics]], [[chaos theory]], and the [[self-organizing systems|self-organization of systems]].

===Pure logic===

There is also such a thing as a [[logical system]]. 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]] 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]] such as a [[theorem]]. Logic has been applied to categories such as [[taxonomy (general)|taxonomy]], [[ontology]], [[educational assessment|assessment]], and [[hierarchies]].

===Strategic thinking===
In 1988, military strategist, [[John A. Warden III]] introduced the [[Warden's Five Rings|Five Ring System]] model in his book, ''[[The Air Campaign]]'', contending that any complex system could be broken down into five concentric rings. Each ring—Leadership, Processes, Infrastructure, Population and Action Units—could be used to isolate key elements of any system that needed change. The model was used effectively by [[Air Force]] planners in the [[First Gulf War]].<ref>{{cite book |last=Warden |first=John A. III |title=The Air Campaign: Planning for Combat |publisher=National Defense University Press |location=Washington, D.C. |date=1988 |isbn=978-1-58348-100-4 |author-link=John A. Warden III}}</ref><ref>{{cite book |last=Warden |first=John A. III |date=September 1995 |chapter=Chapter 4: Air theory for the 21st century |chapter-url=http://www.airpower.maxwell.af.mil/airchronicles/battle/chp4.html |access-date=December 26, 2008 |title=Battlefield of the Future: 21st Century Warfare Issues |chapter-format=in ''Air and Space Power Journal'' |publisher=United States Air Force |archive-date=July 4, 2011 |archive-url=https://web.archive.org/web/20110704071119/http://www.airpower.maxwell.af.mil/airchronicles/battle/chp4.html |url-status=dead }}</ref><ref>{{cite journal |last=Warden |first=John A. III |date=1995 |title=Enemy as a System |journal=Airpower Journal |volume=Spring |issue=9 |pages=40–55 |url=http://www.airpower.maxwell.af.mil/airchronicles/apj/apj95/spr95_files/warden.htm |access-date=2009-03-25 |archive-date=2009-01-13 |archive-url=https://web.archive.org/web/20090113094325/http://www.airpower.maxwell.af.mil/airchronicles/apj/apj95/spr95_files/warden.htm |url-status=dead }}</ref> In the late 1990s, Warden applied his model to business strategy.

==See also==
{{Col-begin}}
{{Col-break}}
;Examples of systems
* [[Physical system]]
* [[Conceptual system]]
* [[Control system]]
* [[Complex system]]
* [[Formal system]]
{{Col-break}}
* [[Information system]]
* [[Management system]]
* [[Social system]]
* [[Meta-system]]
* [[Software system]]
* [[Solar System]]
* [[Human anatomy|Systems in human anatomy]]
* [[Market (economics)|Market]]
* [[Thermodynamic system]]s
{{Col-break}}
{{Portal|Systems science}}
;Related topics
* [[Glossary of systems theory]]
* [[Complexity]]
* [[Complexity theory and organizations]]
* [[Black box]]
* [[System of systems]]
* [[System of systems engineering]]
* [[Systems art]]
{{col-end}}

==References==
{{Reflist}}

==Bibliography==
{{columns-list|colwidth=30em|
* Alexander Backlund (2000). "[https://www.emeraldinsight.com/doi/abs/10.1108/03684920010322055 The definition of system]". In: ''Kybernetes'' Vol. 29 nr. 4, pp.&nbsp;444–451.
* [[Kenneth D. Bailey (sociologist)|Kenneth D. Bailey]] (1994). ''Sociology and the New Systems Theory: Toward a Theoretical Synthesis''. New York: State of New York Press.
* [[Bela H. Banathy]] (1997). [http://www.newciv.org/ISSS_Primer/asem04bb.html "A Taste of Systemics"], ISSS The Primer Project.
* [[Walter F. Buckley]] (1967). '' Sociology and Modern Systems Theory'', New Jersey: Englewood Cliffs.
* [[Peter Checkland]] (1997). ''Systems Thinking, Systems Practice''. Chichester: John Wiley & Sons, Ltd.
* [[Michel Crozier]], Erhard Friedberg (1981). ''Actors and Systems'', Chicago University Press.
* [[Robert L. Flood]] (1999). ''[http://www.msbkwt.com/joomla/images/FILES2018-19/Library/E-Books/Rethinking-The-Fifth-Discipline.pdf Rethinking the Fifth Discipline: Learning within the unknowable]''. London: Routledge.
* [[George J. Klir]] (1969). Approach to General Systems Theory, 1969.
* [[Brian Wilson (systems scientist)|Brian Wilson]] (1980). ''Systems: Concepts, methodologies and Applications'', John Wiley
* Brian Wilson (2001). ''Soft Systems Methodology—Conceptual model building and its contribution'', J.H.Wiley.
* Beynon-Davies P. (2009). ''Business Information + Systems''. Palgrave, Basingstoke. {{ISBN|978-0-230-20368-6}}
}}

==External links==
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{{Wiktionary}}
{{wikiquote}}
* [http://www.physicalgeography.net/fundamentals/4b.html ''Definitions of Systems and Models''] by Michael Pidwirny, 1999–2007.
* [http://www.muellerscience.com/SPEZIALITAETEN/System/Lit.System%281556-2001%29.htm ''Publications with the title "System" (1600–2008)''] by Roland Müller.
* [http://www.muellerscience.com/SPEZIALITAETEN/System/System_Definitionen.htm ''Definitionen von "System" (1572–2002)''] by Roland Müller, (most in German).

{{Systems engineering}}
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[[Category:Systems|*]]
[[Category:Concepts in metaphysics]]