The mother board is located inside the main unit and contains the core circuitry of the computer, including the CPU. It also contains "slots" that other circuit cards such can be plugged into to add extra functions to the computer, such as a modem, networking, video acceleration, or a television tuner. The functions provided by these add-on cards (or daughter cards) are often absorbed into the motherboard as new technology is introduced. Modems, networking, sound, graphics, hard drive controllers, and USB adapters are examples of technology introduced as add-on cards, but now commonly found on the motherboard.
