At the heart of all computing is the Information Processing Cycle, a four-stage sequence that turns raw data into useful information: Input (entering data), Processing (manipulating data via the CPU), Output (presenting results), and Storage (saving data for future use).

Computers are categorized by their size and purpose. Personal computers for individual use include desktops, laptops, and tablets. Mobile devices, like smartphones, blend communication and computing. Multi-user systems serve networks and large organizations: servers manage shared resources, mainframes handle massive transaction volumes, and supercomputers perform intense scientific calculations.

The physical hardware that enables this consists of several core components. The Central Processing Unit (CPU) acts as the computer's brain, executing instructions via its control unit and arithmetic logic unit. Memory (RAM) provides fast, temporary workspace for active data, while storage devices (HDDs/SSDs) offer permanent, high-capacity data retention. All components connect via the motherboard, the main circuit board. Finally, input devices (like keyboards and mice) and output devices (like monitors and printers) facilitate interaction between the user and the machine.