personal computer (PC), small but powerful computer primarily used in an office or home without the need to be connected to a larger computer. PCs evolved after the development of the microprocessor made possible the hobby-computer movement of the late 1970s, when some computers were built from components or kits. In the early 1980s the first low-cost, fully assembled units were mass-marketed. The typical configuration consists of a video display, keyboard, mouse, logic unit and memory, storage device and, often, a modem ; multimedia computers add a sound-reproduction adapter, stereo speakers, and a compact disc (CD-ROM) drive to this configuration so that material can be presented in a combination of animation, graphics, sound, text, and video. Decreases in component size have made it possible to build portable PCs, or laptops