The idea of a cylinder lock is that a flat key with serrated edges is pushed into the keyhole, which is located in the plug in the center of the cylinder. Pins protruding through holes into the plug glide up and down as the key is inserted. Springs above the pins put continuous pressure on the the top and bottom pins. The right key will make the pins line up in the right spot, and the lock turns, unlocking the dead bolt or lockset.

When was the first lock invented?
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Old-fashioned keys weren't flat, as modern keys are. |
Locks of various sorts were invented several time independently, all over the world. We have no idea when or where the first lock was invented, but I can tell you that the oldest known lock was found in the ruins of the Khorsabad Palace, near Nineveh, in the ancient Assyrian empire. (This empire was located in what we now call the Middle East, in parts of Iraq, Syria, Iran, and Turkey.) The lock is about 4,000 years old!
Learn more about the history of locks here.
We may soon be able to use an app to open our doors! I would love, love, love this!
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