Rekeying normally refers to the ability to change a lock so that a different key may operate it. Lock re-key is something that should definitely be done whenever you purchase new property to assure security. Rekeying is a process of changing the configuration of the lock so a new key will function while the old one will not. Rekeying may be done without replacement of the entire lock. Keys may have been lost or stolen, and the orginal keys may have never been changed.