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"Software" redirects here. For other uses, see Software (disambiguation).

Computer software (or simply software) is that part of a computer system that consists of encoded information, as opposed to the physical computer equipment (hardware) which is used to store and process this information. The term is roughly synonymous with computer program but is more generic in scope.

The term "software" was first used in this sense by John W. Tukey in 1957. In computer science and software engineering, computer software is all information processed by computer systems, programs and data. The concept of software was first proposed by Alan Turing in an essay.

Contents 1 Relationship to hardware 2 Relationship to data 3 System, application and programming software 4 Software program and library 5 Users see three layers of software 6 Software creation 7 Software operation 8 Software quality and reliability 9 Software patents 10 See also

Relationship to hardware

Computer software is so called in contrast to computer hardware, which is the physical substrate which is required to store and execute (or run) the software. In computers, software is loaded in RAM and executed on the central processing unit. At the lowest level, software consists of a machine language specific to an individual processor. Machine language consists of groups of binary values signifying processor instructions and data. Software is generally written in high-level languages that are easy and efficient for humans to use. High-level languages are compiled into machine language.

Relationship to data

Software has historically been considered an intermediary between electronic hardware and data, which the hardware processes according to instructions defined by the software. As computational science becomes increasingly complex, the distinction between software and data becomes less precise. Data has generally been considered as either the output or input of software. However, data is not the only possible output or input. For example, configuration information can also be considered input, although not necessarily considered data. The output of a particular piece of software may be the input for another piece of software. Therefore, software may be considered an interface between hardware, data, or software.

System, application and programming software

Practical computer systems divide software into three major classes: system software, application software and programming software, although the distinction is somewhat arbitrary, and often blurred.

System software helps run the computer hardware and computer system. It includes operating systems, device drivers, diagnostic tools, servers, windowing systems, utilities and more.

Application software allows a user to accomplish one or more specific tasks. Typical applications include office suites, business software, educational software, databases and computer games. Most application software has a graphical user interface (GUI).

Programming software usually provides some useful tools to help programmer to write computer programs and software using different programming language in a more convenient way. The tools include text editor, compiler, interpreter, linker, debugger, and so on. Integrated development environment (IDE) merges those tools in a software bundle, and programmer may not need to type a lot of commands for compiling, interpreter, debugging, tracing, and etc., because IDE mostly has a GUI.

Software program and library

Software program is usually the directly executable part of a software. Software libraries are software components that are used by stand-alone programs, but which cannot be executed on their own.

Users see three layers of software

Users often see things differently than programmers. People who use modern general purpose computers (as opposed to embedded systems) usually see three layers of software performing a variety of tasks: platform, application, and user software.

Platform software 

Platform includes the basic input-output system (often described as firmware rather than software), device drivers, an operating system, and typically a graphical user interface which, in total, allow a user to interact with the computer and its peripherals (associated equipment). Platform software often comes bundled with the computer, and users may not realize that it exists or that they have a choice to use different platform software.

Application software 

Application software or Applications are what most people think of when they think of software. Typical examples include office suites and video games. Application software is often purchased separately from computer hardware. Sometimes applications are bundled with the computer, but that does not change the fact that they run as independent applications. Applications are almost always independent programs from the operating system, though they are often tailored for specific platforms. Most users think of compilers, databases, and other "system software" as applications.

User-written software 

User software tailors systems to meet the users specific needs. User software include spreadsheet templates, word processor macros, scientific simulations, graphics and animation scripts. Even email filters are a kind of user software. Users create this software themselves and often overlook how important it is.

See also: Software architecture.

Software creation

Look back to Computer software

Software operation

Computer software has to be "loaded" into the computer's storage (also known as memory and RAM).

Once the software is loaded, the computer is able to operate the software. Computers operate by executing the computer program. This involves passing instructions from the application software, through the system software, to the hardware which ultimately receives the instruction as machine code. Each instruction causes the computer to carry out an operation -- moving data, carrying out a computation, or altering the flow of instructions.

Kinds of software by operation: computer program as executable, source code or script, configuration.

Software quality and reliability

Software reliability considers the errors, faults, and failures related to the creation and operation of software.

See Software quality, Software testing, and Software reliability.

Software patents

The issue of software patents is very controversial, since while patents protect the ideas of "inventors", they are widely believed to hinder software development. See Hacker ethic

See also

• Shared meanings: System software, Application software, Computer programs,

• Computing
• Computer programming
  • Programming languages
  • Text editors
  • Compilers
  • Algorithms
  • Software development process
  • Software development tools
  • Software maintenance
  • Software optimization
  • Application Programming Interface (API)
  • Software brittleness
• Software engineering

• Software licenses
  • Open source software
  • Software piracy
• Software as a Service
• Shovelware
• Freeware
• Postcardware
• Shareware
• Origins of computer terms
• Uninstaller
• Free software

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