A deadbolt is a locking mechanism distinct from a spring bolt lock because it cannot be moved to the open position except by rotating the lock cylinder with the appropriate key. Often used to secure doors, a deadbolt provides a higher level of security than the more common spring bolt due to its design, which resists physical attacks, picking, and forced entry. The mechanism consists of a bolt that slides into the door jamb and strike plate of a door frame. When engaged, the bolt extends from the lock into the door frame, anchoring the door to its frame.
Deadbolts come in two main varieties: single and double cylinder. A single cylinder deadbolt is operated with a key from the outside and a turn knob from the inside, while a double cylinder model requires a key for operation both outside and inside, offering enhanced security but potentially complicating escape in an emergency. Advanced versions may include features such as saw-resistant bolts, hardened pins that prevent drilling, and captive key functions that allow a key to operate like a knob for convenience, enhancing security without sacrificing usability. The selection of a deadbolt involves considering door type, material, and the desired level of security, balancing ease of use against potential threats.