the interface between your computer and your monitor. These days they're being built into the motherboard chipset and sharing SDRAM with the rest of the system.

So I suppose it's not a card at all, but a chip .. well, firmware on a chip, anyway. . .

Video Cards are essential for looking at pictures of naked women

Your video card is only on your motherboard if it is crappy. Big computer companies like to put cheap chips (often from ATI - they are probably have the biggest market share just from this practice) directly on the motherboard.

A real video card is seperate and will plug into a slot on the motherboard. Most video cards today use AGP slots, which were developed just for video cards. Older ones may use PCI but this is slower.