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Glossary - R to Z
RealAudio
A sound-streaming technology developed by Performance Technologies for efficient transmission of sound over a low-speed Internet link (for example, via a 14.4Kbps or 28.8Kbps modem link). While the basic mechanism for playing sounds via the Web is to download an entire sound file and then play it, RealAudio streams play as they download.
TCP/IP (Transmission Control Protocol/Internet Protocol)
This is the suite of protocols that defines the Internet. Originally designed for the UNIX operating system, TCP/IP software is now included with every major kind of computer operating system. To be truly on the Internet, your computer must have TCP/IP software.
TWAIN (Technology Without An Interesting Name)
TWAIN is a standard for acquiring images from image scanners: an image capture API for Microsoft Windows and Apple Macintosh operating systems. The word TWAIN is not officially an acronym.
The standard was first released in 1992. It is currently ratified at version 2.0 as of 28 November 2005 and is maintained by the TWAIN Working Group. TWAIN is typically used as an interface between image processing software and a scanner or digital camera.
The disadvantage of TWAIN is that it does not separate the user-interface from the driver of a device. This makes it difficult to provide transparent network access. Whenever an application loads a TWAIN driver it is completely unattachable from the supplied manufacturer's GUI. To be precise, it is not a fault of TWAIN specification but of such device drivers, because they are not fully compliant with TWAIN.
UPS (Uninterruptible Power Supply)
A backup power unit that provides continuous power when the normal power supply is interrupted. UPS systems can be stand-by, only supplying power when the regular supply is interrupted, or fulltime, relying on regular power and/or batteries to supply it while it supplies power to the protected device. A UPS is not necessary on most computer systems, but can be important on systems that need to be up 24 hours a day, such as servers.
VOIP (Voice Over IP)
A specification and various technologies used to allow making telephone calls over IP networks, especially the Internet.
Just as modems allow computers to connect to the Internet over regular telephone lines, VOIP technology allows humans to talk over Internet connections.
Costs for VOIP calls can be a lot lower than for traditional telephone calls. Because the IP networks are packet-switched this allows for vastly different ways of handling connections and more efficient use of network resources.
WAV (WAVeform)
A file extension which indicates sound information stored in digital form for use by Windows. By using a 'sound card' such files can be 'played' to produce good quality output.
XHTML (eXtensible HyperText Markup Language)
Basically HTML expressed as valid XML. XHTML is intended to be used in the same places you would use HTML (creating web pages) but is much more strictly defined, which makes it a lot easier to create sofware that can read it, edit it, check it for errors, etc.
An explanation of computer terms 
