Glossary of Computer Terms

Computer Terms Glossary

This page is meant to serve as a guide to the vast quantity of computer terms and acronyms in common use for the casual computer user. It is divided into two main sections, the first is dedicated to the basics and is meant more for beginners, while the second is meant instead to be used as a reference. In reality many of the terms in the second section are still quite common; the first section was deliberately kept as short as possible.

Terms in the second section may be looked up by either using the "find in page" function of your browser, or by appending "#term" (without the quotes and where term is the term of interest) to the "URL" or "go to" section of your browser, keeping in mind that case matters. The best method of searching for a term though is to use the Search Interface that will return not only the specific term sought but also other entries that reference it. Be aware that the terms referenced in the second part of this page will freely assume familiarity with the first part.

If you are instead actually trying to figure out what a particular filename extension means, you might instead try the filename extensions page.

If you want something added or see a problem with something already here (but keep in mind this guide is not meant to be overly technical) please send .


The non-physical portion of the computer; the part that exists only as data; the programs. Another term meaning much the same is "code".
An program used to perform various calculations. It is especially popular for financial applications. Some common spreadsheets include Lotus 123, Excel, OpenOffice Spreadsheet, Octave, Gnumeric, AppleWorks Spreadsheet, Oleo, and GeoCalc.


A scanner is a piece of hardware that will examine a picture and produce a computer file that represents what it sees. A digital camera is a related device. Each has its own limitations.
Scheme is a typically interpreted computer language. It was created in 1975 in an attempt to make Lisp simpler and more consistent. Scheme is a fairly portable language, but is not particularly fast.
A script is a series of OS commands. The term "batch file" means much the same thing, but is a bit dated. Typically the same sort of situations in which one would say DOS instead of OS, it would also be appropriate to say batch file instead of script. Scripts can be run like programs, but tend to perform simpler tasks. When a script is run, it is always interpreted.
Loosely speaking, a disk format sometimes used by MS-Windows, Mac OS, AmigaOS, and (almost always) UNIX. Generally SCSI is superior (but more expensive) to IDE, but it varies somewhat with system load and the individual SCSI and IDE components themselves. The quick rundown is that: SCSI-I and SCSI-II will almost always outperform IDE; EIDE will almost always outperform SCSI-I and SCSI-II; SCSI-III and UltraSCSI will almost always outperform EIDE; and heavy system loads give an advantage to SCSI. Note that although loosely speaking it is just a format difference, it is deep down a hardware difference.
sequential access
This indicates that data cannot be selected without having to skip over earlier data first. This is the way that a cassette or video tape will behave. The other common behavior is called random access.
Loosely speaking, serial implies something that has to be done linearly, one at a time, like people being served in a single check-out line. Serial connections are by their nature less expensive than parallel connections (including things like SCSI) but are typically slower.
A server is a computer designed to provide various services for an entire network. It is typically either a workstation or a mainframe because it will usually be expected to handle far greater loads than ordinary desktop systems. The load placed on servers also necessitates that they utilize robust OSes, as a crash on a system that is currently being used by many people is far worse than a crash on a system that is only being used by one person.
The Standard Generalized Mark-up Language provides an extremely generalized level of mark-up. More common mark-up languages like HTML and XML are actually just popular subsets of SGML.
Shareware is software made for profit that allows a trial period before purchase. Typically shareware can be freely downloaded, used for a period of weeks (or sometimes even months), and either purchased or discarded after it has been learned whether or not it will satisfy the user's needs.
A CLI designed to simplify complex OS commands. Some OSes (like AmigaOS, the Hurd, and UNIX) have built-in support to make the concurrent use of multiple shells easy. Common shells include the Korn Shell (ksh), the Bourne Shell (sh or bsh), the Bourne-Again Shell, (bash or bsh), the C-Shell (csh), etc.
A physical component used to add RAM to a computer. Similar to, but incompatible with, DIMMs.
Smalltalk is an efficient language for writing computer programs. Historically it is one of the first object-oriented languages, and is not only used today in its pure form but shows its influence in other languages like Objective-C.
Solaris is the commercial variant of UNIX currently produced by Sun. It is an industrial strength, nigh bulletproof, powerful multitasking OS that will run on SPARC, x86, and PowerPC based machines.
Generally spam is unwanted, unrequested e-mail or Usenet news. It is typically sent out in bulk to huge address lists that were automatically generated by various robots endlessly searching the Internet and newsgroups for things that resemble e-mail addresses. The legality of spam is a topic of much debate; it is at best only borderline legal, and spammers have been successfully persecuted in some states.
The SPARC is a RISC processor developed by Sun. The design was more or less released to the world, and it is currently produced by around a dozen different companies too numerous to even bother mentioning. It is worth noting that even computers made by Sun typically sport SPARCs made by other companies. A couple different OSes run on SPARC based machines, including Solaris, SunOS, and Linux. Some of the newer SPARC models are called UltraSPARCs.
The term sprite originally referred to a small MOB, usually implemented in hardware. Lately it is also being used to refer to a single image used piecemeal within a Web site in order to avoid incurring the time penalty of downloading multiple files.
SQL (pronounced Sequel) is an interpreted language specially designed for database access. It is supported by virtually every major modern database system.
The window manager used by the OLPC XO. It is made to run on top of Linux.
SunOS is the commercial variant of UNIX formerly produced (but still supported) by Sun.
Scalable Vector Graphics data is an XML file that is used to hold graphical data that can be resized without loss of quality. SVG data can be kept in its own file, or even embedded within a web page (although not all browsers are capable of displaying such data).