PC motherboards usually have several expansion slots of various types. The most common slot still in use today is called PCI which can accept various types of cards. Older motherboards had a special slot called an AGP slot that could accept only a video card and provided much better performance than PCI could. AGP has since been replaced by PCI Express.

Expansion slots let the user easily add some hardware capability to the computer that it originally lacked. For example, if your computer didn't come with any SATA ports, Firewire ports, or a modem, you could buy a card which plugs into the motherboard and adds those ports.

This video card can support up to two monitors because it has a DVI and VGA output. Since DVI is better, use DVI if both your video card and LCD support it. LCDs only need one connection to the video card so don't connect both the DVI and VGA outputs to a single LCD. It won't hurt anything, its just unnecessary and causes more cable clutter.

DVI Output: This is where you connect a digital LCD monitor or high definition TV. DVI offers the best picture quality. DVI cables usually have a white connector.

S-Video Output: This is where you could connect an older TV that lacks a DVI or VGA input. The quality is very poor compared to DVI or VGA.

VGA Output: This is where you connect an older CRT monitor or LCD monitor. VGA cables usually have a blue connector. All CRT's and most low-end LCDs only have VGA inputs.

AGP Connector: This is where the video card connects to the motherboard.

Heat Sink: The video card's processor chip generates heat that must be removed. The heat sink pulls the heat out of the chip. More powerful video cards generate even more heat and have a fan on top of their heat sink, just like a CPU's heat sink.

Everything you see on your monitor is generated by your computer's video processor. Many computers have video built into the motherboard and while the performance is acceptable for tasks such as using the Internet, word processing, etc., it performs poorly on demanding tasks such as playing 3D action games. Also, most video on motherboards only supports a single monitor. Someone would want to install a dedicated video card if they needed better performance for games or to be able to use two or more monitors at once.

Older video cards, like the one pictured above, connect to the motherboard by a slot called an AGP slot. When a card is installed in the motherboard's AGP slot, the on-board video (if any) automatically disables itself. Newer video cards use a type of slot called PCI Express, not to be confused with the white PCI slots, which are much faster than either PCI or AGP.

		An Ethernet card connects a computer to a network. That network can be a local area network, such as in a home or office for sharing files or printers, or it can connect the computer directly to the Internet via a DSL or cable modem
		Firewire ports are used to connect external, portable devices such as hard drives to a computer. Firewire is faster than USB but most PC's lack Firewire ports. If a PC user wants to connect a Firewire device to such a computer, they can add the ports with a card like this.
		Older motherboards typically had two IDE ports on them for connecting up to four hard drives or optical drives. If the motherboard's IDE ports were malfunctioning or the user wanted to connect more devices, they could add a card like this to equip their computer with more IDE ports.
		SATA is a newer way of connecting hard drives and optical drives to a computer. If you have an older computer which lacks SATA ports, or just doesn't have enough, a card like this can be installed.
		This is a 56k dialup fax modem. Before DSL and cable Internet, every computer had one of these. A phone line plugged into the back and the modem dialed a number to access the Internet. Modems like this can still be used today for faxing.