A motherboard is the main circuit board inside a computer that connects and allows communication between all hardware components. It holds important parts such as the CPU, RAM, storage devices, graphics card, and expansion cards, while also providing connectors for peripherals like keyboards, mice, and USB devices.

The motherboard distributes power to components and enables them to work together through built-in circuits, chipsets, and communication pathways. It is considered the backbone of a computer because every major hardware component is connected to it directly or indirectly.