Computer software

Software denotes programs that run on computers. John Tukey, a statistician at Princeton University and Bell Laboratories, is generally credited with introducing the term in 1958 (as well as coining the word bit for binary digit). Initially software referred primarily to what is now called system software—an operating system and the utility programs that come with it, such as those to compile (translate) programs into machine code and load them for execution. This software came with a computer when it was bought or leased. In 1969 IBM decided to “unbundle” its software and sell it separately, and software soon became a major income source for manufacturers as well as for dedicated software firms.

 

Business and personal software

Business software generally must handle large amounts of data but relatively little computation, although that has changed somewhat in recent years. Office software typically includes word processors, spreadsheets, database programs, and tools for designing public presentations.

A spreadsheet is a type of accounting program. Unlike specialized accounting programs (e.g., payroll and office records), an important function of spreadsheets is their ability to explore “What if?” scenarios. A spreadsheet not only holds tables of data but also defines relationships among their rows and columns. For example, if the profit on a product is defined in terms of various costs—materials, manufacturing, and shipping—it is easy to ask “What if we use cheaper materials that require more manufacturing expense?”
A database is an organized collection of data, or records. Databases organize information to answer questions such as “What companies in the Southwest bought more than 100 of our products last year?” or “Which products made by Acme Manufacturing are in low supply?” Such software is often integrated so that a database report or spreadsheet table can be added to a document composed with a word processor, frequently with illustrative graphs. Today even the most trivial data can effortlessly be glorified by presenting it in a polychromatic bar chart with three-dimensional shading.

 

Scientific and engineering software

Scientific software is typically used to solve differential equations. (Differential equations are used to describe continuous actions or processes that depend on some other factors.) Although some differential equations have relatively simple mathematical solutions, exact solutions of many differential equations are very difficult to obtain. Computers, however, can be used to obtain useful approximate solutions, particularly when a problem is split into simpler spatial or temporal parts. Nevertheless, large-scale problems often require parallel computation on supercomputers or clusters of small computers that share the work.
There are numerous standard libraries of equation-solving software—some commercial, some distributed by national organizations in several countries. Another kind of software package does symbolic mathematics, obtaining exact solutions by algebraic manipulations. Two of the most widely used symbolic packages are Mathematica and Maple.
Scientific visualization software couples high-performance graphics with the output of equation solvers to yield vivid displays of models of physical systems. As with spreadsheets, visualization software lets an experimenter vary initial conditions or parameters. Observing the effect of such changes can help in improving models, as well as in understanding the original system.
Visualization is an essential feature of computer-aided engineering (CAE) and computer-aided design (CAD). An engineer can design a bridge, use modeling software to display it, and study it under different loads. CAE software can translate drawings into the precise specification of the parts of a mechanical system. Computer chips themselves are designed with CAD programs that let an engineer write a specification for part of a chip, simulate its behaviour in detail, test it thoroughly, and then generate the layouts for the photolithographic process that puts the circuit on the silicon.
Astronomical sky surveys, weather forecasting, and medical imaging—such as magnetic resonance imaging, CAT scans, and DNA analyses—create very large collections of data. Scientific computation today uses the same kinds of powerful statistical and pattern-analysis techniques as many business applications.

 

Internet and collaborative software

Among the most commonly used personal Internet software are “browsers” for displaying information located on the World Wide Web, newsreaders for reading “newsgroups” located on USENET, file-sharing programs for downloading files, and communication software for e-mail, as well as “instant messaging” and “chat room” programs that allow people to carry on conversations in real time. All of these applications are used for both personal and business activities.
Other common Internet software includes Web search engines and “Web-crawling” programs that traverse the Web to gather and classify information. Web-crawling programs are a kind of agent software, a term for programs that carry out routine tasks for a user. They stem from artificial intelligence research and carry out some of the tasks of librarians, but they are at a severe disadvantage. Although Web pages may have “content-tag” index terms, not all do, nor are there yet accepted standards for their use. Web search engines must use heuristic methods to determine the quality of Web page information as well as its content. Many details are proprietary, but they may use techniques such as finding “hubs” and “authorities” (pages with many links to and from other Web sites). Such strategies can be very effective, though the need for a Web version of card catalogs has not vanished.

• Screen shot of the SETI@home page.

A different kind of Internet use depends on the vast number of computers connected to the Internet that are idle much of the time. Rather than run a “screen-saver” program, these computers can run software that lets them collaborate in the analysis of some difficult problem. Two examples are the SETI@home project, which distributes portions of radio telescope data for analysis that might help in the search for extraterrestrial intelligence (SETI), and the “Great Internet Mersenne Prime Search” (GIMPS), which parcels out tasks to test for large prime numbers.
The Internet has also become a business tool, and the ability to collect and store immense amounts of information has given rise to data warehousing and data mining. The former is a term for unstructured collections of data and the latter a term for its analysis. Data mining uses statistics and other mathematical tools to find patterns of information. For more information concerning business on the Internet, see e-commerce.

 

Games and entertainment

Computer games are nearly as old as digital computers and have steadily developed in sophistication. Chinook, a recent checkers (draughts) program, is widely believed to be better than any human player, and the IBM Deep Blue chess program beat world champion Garry Kasparov in 1996. These programs have demonstrated the power of modern computers, as well as the strength of good heuristics for strategy. On the other hand, such brute-force search heuristics have failed to produce a go-playing program that can defeat even moderately skilled players because there are too many possible moves in this Japanese game for simple quantification.
After board games, the earliest computer games were text-based adventures—in which players explored virtual worlds, sought treasure, and fought enemies by reading and typing simple commands. Such games resembled military simulation programs first used in the early 1950s. Contemporary games, however, depend on high-performance computer graphics. Played on arcade machines, special game computers for home use, or PCs, they use the same capabilities as simulation and visualization programs. A related area is computer-generated (CG) animation for films and video.