# Software

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Instructions a computer can execute

For other uses, see [Software (disambiguation)](/source/Software_(disambiguation)).

Software written in the [JavaScript](/source/JavaScript) language

**Software** consists of [computer programs](/source/Computer_program) that instruct the [execution](/source/Execution_(computing)) of a [computer](/source/Computer).[1] Software also includes design documents and specifications.

The history of software is closely tied to the development of digital computers in the mid-20th century. Early programs were written in the [machine language](/source/Machine_language) specific to the hardware. The introduction of [high-level programming languages](/source/High-level_programming_language) in 1958 allowed for more human-readable instructions, making [software development](/source/Software_development) easier and more portable across different [computer architectures](/source/Computer_architecture). Software in a programming language is run through a [compiler](/source/Compiler) or [interpreter](/source/Interpreter_(computing)) to [execute](/source/Execution_(computing)) on the architecture's hardware. Over time, software has become complex, owing to developments in [networking](/source/Computer_network), [operating systems](/source/Operating_systems), and [databases](/source/Databases).

Software can generally be categorized into two main types:

1. [operating systems](/source/Operating_system), which manage hardware resources and provide services for applications

1. [application software](/source/Application_software), which performs specific tasks for users

The rise of [cloud computing](/source/Cloud_computing) has introduced the new software delivery model [software as a service](/source/Software_as_a_service) (SaaS). In SaaS, applications are hosted by a [provider](/source/Application_service_provider) and [accessed](/source/HTTP) over the [Internet](/source/Internet).

The process of developing software involves several stages. The stages include [software design](/source/Software_design), [programming](/source/Computer_programming), [testing](/source/Software_testing), [release](/source/Software_release_life_cycle), and [maintenance](/source/Software_maintenance). [Software quality assurance](/source/Software_quality_assurance) and [security](/source/Information_security) are critical aspects of software development, as [bugs](/source/Computer_bug) and [security vulnerabilities](/source/Vulnerability_(computing)) can lead to system failures and security breaches. Additionally, legal issues such as software licenses and intellectual property rights play a significant role in the distribution of software products.

## History

Main article: [History of software](/source/History_of_software)

The first use of the word *software* to describe computer programs is credited to mathematician [John Wilder Tukey](/source/John_Tukey) in 1958.[2][3][4] The first programmable computers, which appeared at the end of the 1940s,[5] were programmed in [machine language](/source/Machine_language). Machine language is difficult to debug and not [portable](/source/Portability_(computing)) across different computers.[6] Initially, hardware resources were more expensive than [human resources](/source/Human_resources).[7] As programs became complex, [programmer productivity](/source/Programmer_productivity) became the bottleneck. The introduction of [high-level programming languages](/source/High-level_programming_language) in 1958 [hid](/source/Abstraction_(computing)) the details of the hardware and expressed the underlying [algorithms](/source/Algorithm) into the code.[8][9] Early languages include [Fortran](/source/Fortran), [Lisp](/source/Lisp_(programming_language)), and [COBOL](/source/COBOL).[9]

## Types

See also: [Software categories](/source/Software_categories)

A diagram showing how the [user](/source/User_(computing)) interacts with [application software](/source/Application_software) on a typical [desktop computer](/source/Desktop_computer). The application software layer interfaces with the [operating system](/source/Operating_system), which in turn communicates with the [hardware](/source/Computer_hardware). The arrows indicate information flow.

There are two main types of software:

- [Operating systems](/source/Operating_system) are "the [layer of software](/source/Abstraction_layer) that manages a computer's resources for its users and their [applications](/source/Application_software)".[10] There are three main purposes that an operating system fulfills:[11] - Allocating resources between different applications, deciding when they will receive [central processing unit](/source/Central_processing_unit) (CPU) time or space in [memory](/source/Computer_memory).[11] - Providing an interface that abstracts the details of accessing [hardware](/source/Computer_hardware) details (like physical memory) to make things easier for programmers.[11][12] - Offering common services, such as an interface for accessing network and disk devices. This enables an application to be run on different hardware without needing to be rewritten.[13]

- [Application software](/source/Application_software) runs on top of the operating system and uses the computer's resources to perform a task.[14] There are many different types of application software because the range of tasks that can be performed with modern computers is so large.[15] Applications account for most software[16] and require the [environment](/source/Operating_environment) provided by an operating system, and often other applications, in order to function.[17]

Comparison of on-premise hardware and software, [infrastructure as a service](/source/Infrastructure_as_a_service) (IaaS), [platform as a service](/source/Platform_as_a_service) (PaaS), and [software as a service](/source/Software_as_a_service) (SaaS)

Software can also be categorized by how it is [deployed](/source/Software_deployment). Traditional applications are purchased with a perpetual [license](/source/Software_license) for a specific version of the software, downloaded, and run on hardware belonging to the purchaser.[18] The rise of [the Internet](/source/The_Internet) and [cloud computing](/source/Cloud_computing) enabled a new model, [software as a service](/source/Software_as_a_service) (SaaS),[19] in which the provider hosts the software (usually built on top of rented [infrastructure](/source/Infrastructure_as_a_service) or [platforms](/source/Platform_as_a_service))[20] and provides the use of the software to customers, often in exchange for a [subscription fee](/source/Subscription_fee).[18] By 2023, SaaS products—which are usually delivered via a [web application](/source/Web_application)—had become the primary method that companies deliver applications.[21]

## Development and maintenance

Diagram for a traditional [software development life cycle](/source/Software_development_life_cycle) from 1988. The numbers represent the typical cost of each phase.

Software companies aim to deliver a high-quality product on time and under budget. A challenge is that [software development effort estimation](/source/Software_development_effort_estimation) is often inaccurate.[22] [Software development](/source/Software_development) begins by conceiving the project, evaluating its feasibility, analyzing the business requirements, and making a [software design](/source/Software_design).[23][24] Most software projects speed up their development by [reusing](/source/Software_reuse) or incorporating existing software, either in the form of [commercial off-the-shelf](/source/Commercial_off-the-shelf) (COTS) or [open-source software](/source/Open-source_software).[25][26] [Software quality assurance](/source/Software_quality_assurance) is typically a combination of manual [code review](/source/Code_review) by other engineers[27] and automated [software testing](/source/Software_testing). Due to time constraints, testing cannot cover all aspects of the software's intended functionality, so developers often focus on the most critical functionality.[28] [Formal methods](/source/Formal_method) are used in some safety-critical systems to prove the correctness of code,[29] while [user acceptance testing](/source/User_acceptance_testing) helps to ensure that the product meets customer expectations.[30] There are a variety of [software development methodologies](/source/Software_development_methodologies), which vary from completing all steps in order to concurrent and iterative models.[31] Software development is driven by [requirements](/source/Software_requirements) taken from prospective users, as opposed to maintenance, which is driven by events such as a change request.[32]

Frequently, software is [released](/source/Software_release_life_cycle) in an incomplete state when the development team runs out of time or funding.[33] Despite [testing](/source/Software_testing) and [quality assurance](/source/Software_quality_assurance), virtually all software contains [bugs](/source/Software_bug) where the system does not work as intended. Post-release [software maintenance](/source/Software_maintenance) is necessary to remediate these bugs when they are found and keep the software working as the environment changes over time.[34] New features are often added after the release. Over time, the level of maintenance becomes increasingly restricted before being cut off entirely when the product is withdrawn from the market.[35] As software [ages](/source/Software_aging), it becomes known as [legacy software](/source/Legacy_software) and can remain in use for decades, even if there is no one left who knows how to fix it.[36] Over the lifetime of the product, software maintenance is estimated to comprise 75 percent or more of the total development cost.[37][38]

Completing a software project involves various forms of expertise, not just in [software programmers](/source/Software_programmer) but also testing, documentation writing, [project management](/source/Software_project_management), [graphic design](/source/Graphic_design), [user experience](/source/User_experience), user support, [marketing](/source/Marketing), and fundraising.[39][40][24]

## Quality and security

Main articles: [Software quality](/source/Software_quality) and [Computer security](/source/Computer_security)

[Software quality](/source/Software_quality) is defined as meeting the stated requirements as well as customer expectations.[41] Quality is an overarching term that can refer to a code's correct and efficient behavior, its reusability and [portability](/source/Porting), or the ease of modification.[42] It is usually more cost-effective to build quality into the product from the beginning rather than try to add it later in the development process.[43] Higher quality code will reduce lifetime cost to both suppliers and customers as it is more reliable and [easier to maintain](/source/Maintainability).[44][45] Software failures in [safety-critical systems](/source/Safety-critical_system) may result in serious harm, including injury or death.[44] By some estimates, the cost of poor quality software can be as high as 20 to 40 percent of sales.[46] Despite developers' goal of delivering a product that works entirely as intended, virtually all software contains bugs.[47]

The rise of the Internet also greatly increased the need for [computer security](/source/Computer_security) as it enabled malicious actors to conduct [cyberattacks](/source/Cyberattack) remotely.[48][49] If a bug creates a security risk, it is called a [vulnerability](/source/Vulnerability_(computing)).[50][51] [Software patches](/source/Software_patch) are often released to fix identified vulnerabilities, but those that remain unknown ([zero days](/source/Zero-day_(computing))) as well as those that have not been patched are still liable for exploitation.[52] Vulnerabilities vary in their ability to be [exploited](/source/Exploit_(computer_security)) by malicious actors,[50] and the actual risk is dependent on the nature of the vulnerability as well as the value of the surrounding system.[53] Although some vulnerabilities can only be used for [denial of service](/source/Denial_of_service) attacks that compromise a system's availability, others allow the attacker to [inject](/source/Code_injection) and run their own code (called [malware](/source/Malware)), without the user being aware of it.[50] To thwart cyberattacks, all software in the system must be designed to withstand and recover from external attack.[49] Despite efforts to ensure security, a significant fraction of computers are infected with malware.[54]

## Encoding and execution

### Programming languages

Main article: [Programming language](/source/Programming_language)

The [source code](/source/Source_code) for a computer program in [C](/source/C_(programming_language)). The gray lines are [comments](/source/Comment_(computer_programming)) that explain the program to humans. When [compiled](/source/Compiled) and [run](/source/Execution_(computing)), it will output "[Hello, world!](/source/%22Hello%2C_World!%22_program)".

Programming languages are the format in which software is written. Since the 1950s, thousands of different programming languages have been invented; some have been in use for decades, while others have fallen into disuse.[55] Some definitions classify [machine code](/source/Machine_code)—the exact instructions directly implemented by the hardware—and [assembly language](/source/Assembly_language)—a more human-readable alternative to machine code whose statements can be translated one-to-one into machine code—as programming languages.[56] Programs written in the [high-level programming languages](/source/High-level_programming_languages) used to create software share a few main characteristics: knowledge of machine code is not necessary to write them, they can be [ported](/source/Ported) to other computer systems, and they are more concise and human-readable than machine code.[57] They must be both human-readable and capable of being translated into unambiguous instructions for computer hardware.[58]

### Compilation, interpretation, and execution

The invention of high-level programming languages was simultaneous with the [compilers](/source/Compiler) needed to translate them automatically into machine code.[59] Most programs do not contain all the resources needed to run them and rely on external [libraries](/source/Software_library). Part of the compiler's function is to link these files in such a way that the program can be executed by the hardware. Once compiled, the program can be saved as an [object file](/source/Object_file) and the [loader](/source/Loader_(computing)) (part of the operating system) can take this saved file and [execute](/source/Execution_(computing)) it as a [process](/source/Process) on the computer hardware.[60] Some programming languages use an [interpreter](/source/Interpreter_(computing)) instead of a compiler. An interpreter converts the program into machine code at [run time](/source/Execution_(computing)), which makes them 10 to 100 times slower than compiled programming languages.[61][62]

## Legal issues

### Liability

Main article: [Software product liability](/source/Software_product_liability)

Software is often released with the knowledge that it is incomplete or contains bugs.[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] Purchasers knowingly buy it in this state,[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] which has led to a legal regime where [liability](/source/Product_liability) for software products is significantly curtailed compared to other products.[63]

### Licenses

Main articles: [Software license](/source/Software_license) and [Software copyright](/source/Software_copyright)

[Blender](/source/Blender_(software)), a [free software](/source/Free_software) program

Since the mid-1970s, software and its source code have been protected by [copyright law](/source/Copyright_law) that vests the owner with the exclusive right to copy the code. The underlying ideas or algorithms are not protected by copyright law, but are sometimes treated as a [trade secret](/source/Trade_secret) and concealed by such methods as [non-disclosure agreements](/source/Non-disclosure_agreement).[64] A [software copyright](/source/Software_copyright) is often owned by the person or company that financed or made the software (depending on their contracts with employees or [contractors](/source/Independent_contracting_in_the_United_States) who helped to write it).[65] Some software is in the [public domain](/source/Public_domain) and has no restrictions on who can use it, copy or share it, or modify it; a notable example is software written by the [United States Government](/source/Federal_government_of_the_United_States).[*[citation needed](https://en.wikipedia.org/wiki/Wikipedia:Citation_needed)*] [Free and open-source software](/source/Free_and_open-source_software) also allow free use, sharing, and modification, perhaps with a few specified conditions.[65] The use of some software is governed by an agreement ([software license](/source/Software_license)) written by the copyright holder and imposed on the user. [Proprietary software](/source/Proprietary_software) is usually sold under a restrictive license that limits its use and sharing.[66] Some free software licenses require that modified versions must be released under the same license, which prevents the software from being sold or distributed under proprietary restrictions.[67]

### Patents

Main articles: [Software patent](/source/Software_patent) and [Software patent debate](/source/Software_patent_debate)

[Patents](/source/Patent) give an inventor an exclusive, time-limited license for a novel product or process.[68] Ideas about what software could accomplish are not protected by law and concrete implementations are instead covered by [copyright law](/source/Copyright_law). In some countries, a requirement for the claimed invention to have an effect on the physical world may also be part of the requirements for a software patent to be held valid.[69] [Software patents](/source/Software_patent) have been [historically controversial](/source/Software_patent_debate). Before the 1998 case *[State Street Bank & Trust Co. v. Signature Financial Group, Inc.](/source/State_Street_Bank_%26_Trust_Co._v._Signature_Financial_Group%2C_Inc.)*, software patents were generally not recognized in the United States. In that case, the [Supreme Court](/source/Supreme_Court_of_the_United_States) decided that business processes could be patented.[70] Patent applications are complex and costly, and lawsuits involving patents can drive up the cost of products.[71] Unlike copyrights, patents generally only apply in the jurisdiction where they were issued.[72]

## Impact

Further information: [Information Age](/source/Information_Age)

Computer-generated simulations are one of the advances enabled by software.[73]

Engineer [Capers Jones](/source/Capers_Jones) writes that "computers and software are making profound changes to every aspect of human life: education, work, warfare, entertainment, medicine, law, and everything else".[74] It has become ubiquitous in [everyday life](/source/Everyday_life) in [developed countries](/source/Developed_countries).[75] In many cases, software augments the functionality of existing technologies such as household [appliances](/source/Home_appliance) and [elevators](/source/Elevator).[76] Software also spawned entirely new technologies such as [the Internet](/source/The_Internet), [video games](/source/Video_games), [mobile phones](/source/Mobile_phones), and [GPS](/source/GPS).[76][77] New methods of communication, including [email](/source/Email), [forums](/source/Internet_forum), [blogs](/source/Blog), [microblogging](/source/Microblogging), [wikis](/source/Wiki), and [social media](/source/Social_media), were enabled by the Internet.[78] Massive amounts of knowledge exceeding any paper-based library are now available with a quick [web search](/source/Web_search).[77] Most creative professionals have switched to software-based tools such as [computer-aided design](/source/Computer-aided_design), [3D modeling](/source/3D_modeling), digital [image editing](/source/Image_editing), and [computer animation](/source/Computer_animation).[73] Almost every complex device is controlled by software.[77]

## See also

- [List of AI-assisted software development tools](/source/List_of_AI-assisted_software_development_tools)

## References

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1. **[^](#cite_ref-FOOTNOTETracy2021121_59-0)** [Tracy 2021](#CITEREFTracy2021), p. 121.

1. **[^](#cite_ref-FOOTNOTETracy2021122–123_60-0)** [Tracy 2021](#CITEREFTracy2021), pp. 122–123.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022375_61-0)** [O'Regan 2022](#CITEREFO'Regan2022), p. 375.

1. **[^](#cite_ref-FOOTNOTESebesta201228_62-0)** [Sebesta 2012](#CITEREFSebesta2012), p. 28.

1. **[^](#cite_ref-FOOTNOTEKitchinDodge201136–37_63-0)** [Kitchin & Dodge 2011](#CITEREFKitchinDodge2011), pp. 36–37.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022394–396_64-0)** [O'Regan 2022](#CITEREFO'Regan2022), pp. 394–396.

1. ^ [***a***](#cite_ref-FOOTNOTEO'Regan2022403_65-0) [***b***](#cite_ref-FOOTNOTEO'Regan2022403_65-1) [O'Regan 2022](#CITEREFO'Regan2022), p. 403.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022394,_404_66-0)** [O'Regan 2022](#CITEREFO'Regan2022), pp. 394, 404.

1. **[^](#cite_ref-FOOTNOTELanger201644–45_67-0)** [Langer 2016](#CITEREFLanger2016), pp. 44–45.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022395_68-0)** [O'Regan 2022](#CITEREFO'Regan2022), p. 395.

1. **[^](#cite_ref-69)** Gerardo Con Díaz, "The Text in the Machine: American Copyright Law and the Many Natures of Software, 1974–1978", *Technology and Culture* 57 (October 2016), 753–79.

1. **[^](#cite_ref-FOOTNOTEJones201419_70-0)** [Jones 2014](#CITEREFJones2014), p. 19.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022398_71-0)** [O'Regan 2022](#CITEREFO'Regan2022), p. 398.

1. **[^](#cite_ref-FOOTNOTEO'Regan2022399_72-0)** [O'Regan 2022](#CITEREFO'Regan2022), p. 399.

1. ^ [***a***](#cite_ref-FOOTNOTEManovich2013333_73-0) [***b***](#cite_ref-FOOTNOTEManovich2013333_73-1) [Manovich 2013](#CITEREFManovich2013), p. 333.

1. **[^](#cite_ref-FOOTNOTEJones201432_74-0)** [Jones 2014](#CITEREFJones2014), p. 32.

1. **[^](#cite_ref-FOOTNOTEKitchinDodge2011iv_75-0)** [Kitchin & Dodge 2011](#CITEREFKitchinDodge2011), p. iv.

1. ^ [***a***](#cite_ref-FOOTNOTEKitchinDodge20115_76-0) [***b***](#cite_ref-FOOTNOTEKitchinDodge20115_76-1) [Kitchin & Dodge 2011](#CITEREFKitchinDodge2011), p. 5.

1. ^ [***a***](#cite_ref-FOOTNOTEJones2014xxviii_77-0) [***b***](#cite_ref-FOOTNOTEJones2014xxviii_77-1) [***c***](#cite_ref-FOOTNOTEJones2014xxviii_77-2) [Jones 2014](#CITEREFJones2014), p. xxviii.

1. **[^](#cite_ref-FOOTNOTEManovich2013329_78-0)** [Manovich 2013](#CITEREFManovich2013), p. 329.

### Sources

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v t e Software digital distribution platforms App store Cloud gaming Content delivery network Digital library Digital distribution of video games Over-the-air update Package manager Software distribution List of mobile app distribution platforms Android Active Personal computers Amazon Digital Game Store Battle.net Big Fish Games Chrome Web Store Direct2Drive Discord DLsite Discover DMM Games EA Epic Games Store Flathub GameHouse GamersGate Gamesplanet Game Jolt GOG.com Humble Store IndieGala itch.io iWin MacGameStore MacUpdate Mac App Store Meta Horizon Store Microsoft Store MSN Games Nutaku Pogo.com Pokki PureOS Software Center Rockstar Games Social Club Snap Store Steam Ubisoft Connect Viveport WeGame WildTangent Consoles Microsoft Store Nintendo eShop PlayStation Store Mobile devices § Amazon Appstore Apple App Store Appland Aptoide Cafe Bazaar Cydia DLsite Epic Games Store F-Droid Galaxy Store GetJar Google Play Huawei AppGallery Meta Horizon Store MiKandi Nutaku OpenStore PureOS Software Center RuStore Tencent Appstore SlideME TapTap Viveport Arcade NESiCAxLive Defunct Allmyapps BlackBerry World Club Nokia Desura Digital River Download! GameAgent GameLine GameShadow GameTap Games for Windows Marketplace Handango Impulse Indie Royale Intel AppUp Kartridge Kazaa N-Gage Nokia Store Opera Mobile Store PlayCable Playism PlayNow Arena RealArcade Robot Cache Satellaview Sega Channel Sega Meganet Stardock Central Triton Ubuntu App Store Ubuntu Software Center Vodafone live! Wii Shop Channel Windows Marketplace Windows Marketplace for Mobile Windows Phone Store Xbox Games Store Xbox Live Arcade Yahoo! Games Zune Marketplace § Also includes smart TVs and standalone VR headsets Category Portal

[Portal](https://en.wikipedia.org/wiki/Wikipedia:Contents/Portals):
- [Free and open-source software](https://en.wikipedia.org/wiki/Portal:Free_and_open-source_software)

**Software** at Wikipedia's [sister projects](https://en.wikipedia.org/wiki/Wikipedia:Wikimedia_sister_projects):

- [**Media**](https://commons.wikimedia.org/wiki/Software) from Commons
- [**Quotations**](https://en.wikiquote.org/wiki/Software) from Wikiquote
- [**Textbooks**](https://en.wikibooks.org/wiki/Shelf:Computer_software) from Wikibooks
- [**Resources**](https://en.wikiversity.org/wiki/Software) from Wikiversity

Authority control databases International GND FAST National United States 2 France BnF data Japan Czech Republic Spain Israel Other Yale LUX

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Adapted from the Wikipedia article [Software](https://en.wikipedia.org/wiki/Software) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Software?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.