A motherboard is the central or primary printed circuit board (PCB) making up a complex electronic system, such as a modern computer or laptop. It is also known as a mainboard, baseboard, system board, planar board, or, on Apple computers, a logic board, and is sometimes abbreviated casually as mobo.
Most motherboards produced today are designed for so-called IBM-compatible computers, which held over 96% of the global personal computer market in 2005. Motherboards for IBM-compatible computers are specifically covered in the PC motherboard article.
A motherboard, like a backplane, provides the electrical connections by which the other components of the system communicate, but unlike a backplane also contains the central processing unit and other subsystems such as real time clock, and some peripheral interfaces.
A typical desktop computer is built with the microprocessor, main memory, and other essential components on the motherboard. Other components such as external storage, controllers for video display and sound, and peripheral devices are typically attached to the motherboard via edge connectors and cables, although in modern computers it is increasingly common to integrate these "peripherals" into the motherboard.
All of the basic circuitry and components required for a computer to function are onboard the motherboard or are connected with a cable. The most important component on a motherboard is the chipset. It often consists of two components or chips known as the Northbridge and Southbridge, though they may also be integrated into a single component. These chips determine, to an extent, the features and capabilities of the motherboard.