About Deadbolts & Deadlatches
There are two types of deadbolt locks. Internal deadbolt locks are installed within the door and consist of three components: a bolt, a thumbturn or key lock cylinder, and a strike plate. The bolt is turned via the thumbturn or key (in the case of a lock cylinder deadbolt) which moves the bolt into the strike plate installed in the doorway. Conversely, all components of surface-mount deadbolts, AKA night latches, are mounted externally with the bolt mechanism installed on the door, and the bolt box aligned on the doorframe or door jamb to receive the bolt. As an option, door bolts are easier to install but typically offer a lesser degree of security.