HardwareSecrets teaches everything you need to know about video connectors found on PCs and CE products: RF, Composite (RCA), S-Video, Component, RGB, VGA, DVI, HDMI, and DisplayPort. You can read it over here.
"There are several types of video connections that you can find on PC and consumer electronics ("CE") products such as TVs, DVD/Blu-Ray players, video game consoles, cable TV receptors ("set-top boxes"), and video projectors. Even though they all serve the same purpose - to connect video signals from one device to another - the video quality obtained by each type of connection and/or the number of features available are completely different. Since you probably want to get the best video quality from your equipment, we've written this tutorial to explain the differences between each kind of connection and when to use each of them, with many tips on how to improve the video quality generated by your equipment."