Lock

Lock, device that fastens shut and prevents the opening of doors, windows, lids, and other objects. Types of lock include key, combination, chain, and electronic. Most common door locks have a bolt that fits into a metal plate in the doorframe. The first key-operated lock, invented in Egypt c.2000 B.C., was a large wooden bolt fastened to the outside of a gate and stabilized by pegs inserted through it; a key raised the pins to free the bolt.