Software

From Wikipedia, the free encyclopedia

For other uses, see Software (disambiguation).

Computer software or simply software is any set of instructions that directs a computer to perform specific operations. Computer software consists of computer programs,libraries and related non-executable data (such as online documentation or digital media). Computer software is non-tangible, contrasted with computer hardware, which is the physical component of computers. Computer hardware and software require each other and neither can be realistically used without the other.

At the lowest level, executable code consists of machine language instructions specific to an individual processor—typically a central processing unit (CPU). A machine languageconsists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a particular storage location inside the computer—an effect that is not directly observable to the user. An instruction may also (indirectly) cause something to appear on a display of the computer system—a state change which should be visible to the user. The processor carries out the instructions in the order they are provided, unless it is instructed to "jump" to a different instruction, or interrupted.

Software written in a machine language is known as "machine code". However, in practice, software is usually written in high-level programming languages that are easier and more efficient for humans to use (closer to natural language) than machine language.^[1] High-level languages are translated into machine language using a compiler or aninterpreter or a combination of the two. Software may also be written in a low-level assembly language, essentially, a vaguely mnemonic representation of a machine language using a natural language alphabet. Assembly language is translated into machine language using an assembler.

Contents

  [hide] 

• 1History
• 2Types of software
  • 2.1Purpose, or domain of use
  • 2.2Nature or domain of execution
  • 2.3Programming tools
• 3Software topics
  • 3.1Architecture
  • 3.2Execution
  • 3.3Quality and reliability
  • 3.4License
  • 3.5Patents
• 4Design and implementation
• 5Industry and organizations
• 6See also
• 7References
• 8External links

History[edit]

Main article: History of software

An outline (algorithm) for what would have been the first piece of software was written by Ada Lovelace in the 19th century, for the planned analytical engine. However, neither the analytical engine nor any software for it were ever created.

The first theory about software—prior to the creation of computers as we know them today—was proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem (decision problem).

This eventually led to the creation of the twin academic fields of computer science and software engineering, which both study software and its creation. Computer science is more theoretical (Turing's essay is an example of computer science), whereas software engineering is focused on more practical concerns.

However, prior to 1946, software as we now understand it—programs stored in the memory of stored-program digital computers—did not yet exist. The very first electronic computing devices were instead rewired in order to "reprogram" them.

Types of software[edit]

On virtually all computer platforms, software can be grouped into a few broad categories.

Purpose, or domain of use[edit]

Based on the goal, computer software can be divided into:

• Application software, which is software that uses the computer system to perform special functions or provide entertainment functionsbeyond the basic operation of the computer itself. There are many different types of application software, because the range of tasks that can be performed with a modern computer is so large—see list of software.
• System software, which is software that directly operates the computer hardware, to provide basic functionality needed by users and other software, and to provide a platform for running application software.^[2] System software includes:
  • Operating systems, which are essential collections of software that manage resources and provides common services for other software that runs "on top" of them. Supervisory programs, boot loaders, shells and window systems are core parts of operating systems. In practice, an operating system comes bundled with additional software (including application software) so that a user can potentially do some work with a computer that only has an operating system.
  • Device drivers, which operate or control a particular type of device that is attached to a computer. Each device needs at least one corresponding device driver; because a computer typically has at minimum at least one input device and at least one output device, a computer typically needs more than one device driver.
  • Utilities, which are computer programs designed to assist users in maintenance and care of their computers.
• Malicious software or malware, which is software that is developed to harm and disrupt computers. As such, malware is undesirable. Malware is closely associated with computer-related crimes, though some malicious programs may have been designed as practical jokes.
• copyright;https://en.wikipedia.org/wiki/Software