Hardware refers to various computer components such as monitors, motherboards, CPUs, RAM, expansion cards, power supplies, optical disk drives, hard disks, keyboards, and mice. It provides essential functions like displaying visual information, serving as the main circuit board that holds other components, processing instructions, providing data storage, adding new capabilities, supplying power, reading optical discs, long-term storage, text input, and pointing/selecting onscreen. Hardware is critical infrastructure that allows computers to function.