Motherboards are the central circuit boards that connect and allow communication between all the components of a computer. The motherboard houses essential components such as the CPU, RAM, and storage connectors, and it provides the necessary slots and ports for additional peripherals. Motherboards come in different form factors, such as ATX, Micro ATX, and Mini ITX, allowing users to choose based on their build size and requirements. Shopping online for motherboards provides a variety of options, with choices for gaming, workstations, and custom PC builds.