A first-come, first-served technique for managing data in a multiuser environment. The first user to access the file or data record prevents, or locks out, other users from accessing it. After the file or record is updated, it is unlocked and available. File and record locking is an essential part of every database management system (DBMS), document management system and any other system that allows data to be updated by multiple users or applications. See also
lock down.