Mortise locks are robust and secure locking mechanisms commonly installed in doors. They are designed to fit inside a rectangular cavity, or mortise, in the door's edge, with the lock body mounted horizontally within the door. Mortise locks typically include a latch mechanism operated by a key and a separate deadbolt for additional security. They offer superior strength and durability compared to surface-mounted locks and are often preferred for both residential and commercial applications due to their reliability and resistance to forced entry.