Motherboard:

This can also be called a main board or a system board.  It is the circuit board that houses the CPU and allows all devices to communicate with it and with each other.  There are different types of motherboards and those types are called form factors.  The form factors are based on the size of the case in which you would place the motherboard.  The most common form factors for today’s desktops are the ATX and Micro-ATX.