Connectors

	PS/2	Used for keyboards (purple) and mice (green) on ATX form factor computers
	5-pin DIN	Used for keyboards on AT form factor computers.  Also used for MIDI, like on the Live!Drive from Creative
	9-pin Serial	Used for mice on AT computers, as well as ATX if you wish.  Also used for external modems, null modems to connect computers together and connecting devices like PDAs, cell phones, etc... to a computer
	25-pin Serial	Found on AT form factor computers, external modems and null modem cables are all  I've seen this port used for but there probably is more
	Parallel	Used for printers, scanners, external CD-ROMs, external ZIP drives and connecting computers together
	USB	Used for mice, keyboards, printers, scanners, ZIP drives, PDAs, external CD-ROMs/hard drives, game controllers, etc... there's just too many to list
	6-pin Firewire and 4-pin Firewire	Used to transfer video from digital video devices to the computer, and connecting external hard drives and ZIP drives. Also used to for connecting two computers together.
	MIDI/Game Port	Used for connecting MIDI devices and game controllers
	Audio Connectors	Used for connecting speakers, microphones and external sound devices
	RJ-11	Found on modems (as well as other phone equipment) for connecting the phone line
	RJ-45	Found on network cards, hubs, switches, routers, etc... for connecting to network cables
	VGA	Used for analog monitors (CRT and some LCD)
	DVI-I	Used for digital monitors (some LCD) but also has an analog signal so that an analog monitor, with the aid of an adapter, can be used
	DVI-D	Used for digital monitors (some LCD)
	S-Video/Composite	Found on video cards to allow the video output to be outputted to TV/VCRs via S-Video or, with the aid of an adapter, Composite (RCA)
	S-Video	Found more on laptops than desktop video cards, does the same as above but does not have the Composite part.