DVD player video outputs from left to right: composite video, s-video, component video
Component-video outputs provide the highest quality video signal to your TV. They are quite rare right now; only the newest high-end TVs can support them. But, if you have such a TV, you'll definitely want a DVD player with component video outputs. There are three separate connectors for component video output.
S-video outputs are more common. S-video provides a very good picture quality, and every DVD player has at least one of these outputs.
Composite-video outputs are the most common type of output, and they provide adequate picture quality. Usually, they have a yellow plastic insert.
DVD player audio outputs
Coaxial digital output and optical digital outputs provide the highest-quality audio. They send the digital sound information to the receiver for decoding. You can use either one of these if you have a Dolby Digital receiver.
5.1 channel is a set of six analog outputs, one for each of the Dolby Digital channels (left front, center front, right front, left rear, right rear and subwoofer). The DVD player decodes the Dolby Digital signal and uses its own DAC to output an analog signal. These are the outputs you'll need to use if you are hooking the DVD player up to a "Dolby Digital ready" receiver. DVD players with 5.1 channel outputs will always have Dolby Digital decoders, and they may or may not have DTS decoders. If you have a "Dolby Digital ready" receiver and you want DTS sound, you will need a DVD player with a built-in DTS decoder.
Stereo outputs carry only the stereo music signal. You would use these if you were hooking your DVD player up to a TV that has only two speakers.