The standard for the way a signal is carried on the cable itself. The industry has settled on a 4-pin mini plug connector.

S-Video does not have any relation to the resolution or refresh rate of the signal. Do not confuse S-Video with S-VHS. S-VHS is a tape/signal standard.

S-Video is a hardware standard that defines the physical cable jacks.

S-Video allows you to bypass the comb filter in a device. Generally, less processing of the signal results in a better picture. The comb filter separates the chroma (color) and luma (brightness) components of a video signal into separate parts. This is also called Y/C, where Y represents brightness and C color. When color and brightness are not separated, when they are combined in the signal, it is called a composite signal. S-Video cables have separate wires for the color and brightness. That is, they carry a Y/C signal. The best picture comes when the color and brightness is separate from the source. VCRs record this way, and DSS broadcasts this way too.

Laserdiscs store a composite picture rather than Y/C separated. Even when the signals have been combined at some point on their way to the monitor, different comb filters perform to different degrees of quality, so one can pick how to connect one’s components to try to use the best comb filter.

Some older sets with S-Video input jacks may actually combine the Y/C in a crude way, making the S-Video input no better than a typical composite signal. Newer sets do not do this.