The document defines and describes several common computer components: a monitor displays visual content and includes a display, circuitry, and enclosure; speakers output audio in response to electrical signals; a mouse is a pointing device that detects two-dimensional motion on a surface; a keyboard uses buttons or keys to input data mechanically or electronically; a printer produces physical copies of electronic documents and graphics; a web cam feeds live video to a computer via connections like USB; a hard disk is a magnetic storage device; a microprocessor incorporates a computer's central processing unit onto an integrated circuit.