The first locks were quite simple—a wooden beam that was slid across a door. This concept, however, only worked if you were inside the room you wanted to lock. To remedy this, ancient Egyptians and Mesopotamians devised “pin-tumbler” locks, basically wooden-beam locks that could be opened from the outside with a wooden key. The beam was released from the tumblers that held it in place, and the key then pushed the beam into the desired...Continue Reading