RDBMS
Relational Database Management System.

RealPlayer
Plug-in from RealNetworks for sound and video file management and streaming.

RealProducer
Encoding software from RealNetworks for converting sound files into RealAudio format.

Registrar
A company specialised in the registering of domain names with the InterNIC.

Relative Path
A partial path relative to the location of the visited page.

RGB Mode
Images in RGB (red, green and blue) mode are displayed on the screen by means of three primary colours.

Rollover
The effect produced by changing the appearance of a graphical element when the mouse pointer moves over it.

Router
Typically a machine, though it can also be software, that acts as a gateway to provide access to network resources, irrespective of the protocols or operating systems the users use.

RTSP
Real Time Streaming Protocol. A client/Server communication protocol that simplifies the distribution of multimedia contents on the Internet.