Below is the official definition for motherboard:
a printed circuit board
A printed circuit board containing the principal components of a computer or other device, with connectors for other circuit boards to be slotted into.
Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive.
Collectively, all these chips that reside on the motherboard are known as the motherboard's chipset.
Usually, on most PCs you can add memory chips directly to the motherboard. You can also upgrade to a faster PC. You can do this by replacing the CPU chip. To add additional core features, you may need to replace the motherboard entirely.
Below are a few of the components in a motherboard:
· A CPU socket
· A power connector
· Slots for the system's main memory
· A chip forms an interface between the CPU, the main memory and other components. It also contains a large heat sink.
· A second chip which controls the input and output (I/O) functions.
· Several connectors
· Slots for one or more hard drives to store files.
· A Read-only memory (ROM) chip, which contains the firmware, or startup instructions for the computer system. This is also called the BIOS.
· A slot for a video or graphics card.
· Additional slots to connect hardware in the form of Peripheral Component Interconnect (PCI) slots.