Definitions:

Techno-babble seems to prevail in the Audio / Visual industry.   A quick description of the salient buzz words and terms are given here.

Composite Video.
Video where the colour and brightness information is mixed.   This produces interference between the signals, cross colour being just one artefact.   For an example, look at a sharp edge on a normal TV picture and you'll notice a running pattern.   S-Video removes this annoyance.

S-Video.
The solution to removing the interference between the colour and brightness information is to keep the signals separate.   This is exactly how S-Video works, by using a separate connection for the colour information than the brightness.   This format is similar to how video pictures are encoded on DVDs and in Digital TV transmissions.

S-VHS.
A superior recording method to VHS.   S-VHS is sometimes used to describe S-Video.   For optimum recording, it is essential to use S-Video video input, not standard composite.

D-VHS.
A new type of VCR.   This stores a digital representation of the video picture to tape.   For optimum recording, it is essential to use S-Video video input, not standard composite.

DVD
Digital Versatile Disc.   A high quality format for use in Home Cinemas.   The replacement for VHS pre-recorded video tapes.   Movies and computer information in a form similar to CDs, but with a greater capacity.    Often included multi-channel sound and various extras, such as the making of the film.

DVD-R
A write-once format of DVD, used in computers as well as DVD recorders.   See also DVD RW / RAM.

DVD RW / RAM
Two competing means to record on to a digital disc.   While a DVD RAM may not be able to be played in the majority of DVD players, an RW disc is able.   Both will write to DVD-R, so the VHS/Betamax type competition isn't as big an issue as you will always be able to make DVD-R discs.

RGB.
Red, Green, Blue.   These are the component colours that are used to create the video picture.   Look closely at your TV and you'll see these.   In a DVD or Digital TV system, the RGB is not true RGB, but rather signals that have been converted for a format not too dissimilar to S-Video.

Component (YUV or YPrPb).
A type of high quality video normally found on US equipment, but increasingly throughout the world.   Component has three signals, Y, U, and V.   Y is a black & white picture with U&V being colour overlays.   Y is the same as would be found in S-Video, but the difference is that U&V are not modulated, and therefore is a higher quality signal.

PAL.
Phase Alternating Line.   The TV system used in the UK and many parts of Europe.   In the UK this is a picture with 625 lines at 50 fields per second.   50 fields per second was chosen to match the line frequency of the mains.   The colour information is located at a carrier frequency of 4.43MHz.

NTSC.
National Television Standards Committee.   The TV system used in the US and Japan.   In the US the picture is 525 lines at 60 fields per second.   The colour information is located at a carrier frequency of 3.58MHz.

Laserdisc.
The previous high quality source for Home-Cinemas, now eclipsed by Digital Versatile Disc.

Digital Set-top Box.
A box for receiving either satellite or terrestrial digital video.   In the UK the main providers are FreeView, Sky and NTL/Telewest Cable.

Dolby Digital.
A multi channel surround sound system, by far the most popular on DVDs.   In it's basic surround from, five channels and a bass are encoded.   Each of the five channels has the fully range of frequency response, while strictly not quite CD quality (see Compression  / Encoding), the sound quality is excellent.   Dolby Digital can also be used for mono, stereo, and higher numbers of channels.

DTS (Digital Theatre Sound).
Rival to Dolby Digital, many claim DTS to be superior.   Not as common on DVDs.

MPEG 5.1.
Another rival to Dolby Digital.   Supposed to be the European 5.1 standard and to be exclusively used on European region DVDs, but fortunately Dolby Digital is now the standard and MPEG 5.1 will only be seen on early UK DVDs.

Compression / Encoding.
Reducing the data required to store of transmit information by excluding less important parts.   Most common are MPEG type compression, an example is MP3 for audio.   With compressed audio it is common for 80% of the information to be discarded, but still to keep a detailed sound.   CD audio is uncompressed and is still the best source for digital audio.