mainboard

This is the circuit board that holds all the componets of your computer, including the CPU, the memory, and all the expansion cards. Otherwise called "the motherboard".

The PCB inside your computer into which just about everything plugs. Mainboards come in different types for different CPUs and are now able to house either DDR RAM or SDRAM modules.

Some boards are able to accomodate two (or more) CPUs. This is mainly for server computers and high-end workstations.

There are two main form factors available. The older style AT mainboard, which began to disappear with the emergence of the Pentium II boards, and the newer style ATX form factor for the modern computers.

Some mainboards have sound or video built into the PCB. These are usually used by system integrators to make cheap computers for tightass companies that complain when their users see a Blue Screen Of Death every second day.