How Do Locks Work?

Imagine a lock is like a stack of tiny Lego blocks inside your keyhole. When you put your key in, the teeth on the key push up some of these blocks to just the right height.

The keyway has two parts that need to line up perfectly. If even one block is too low or too high, the lock stays shut tight. The key pushes the blocks so they all sit exactly where they need to be.

Inside the lock, there are small springs underneath each block. These springs want to push the blocks down. But once your key lifts them up into a perfect line, called the shear line, they stay there. When you turn the key, it turns the whole stack together like a solid wheel.

You do not need electricity or batteries for this to work. It is all about friction and spring pressure. The harder the springs push down, the harder it is for someone to wiggle the blocks up by mistake with a bobby pin or a hairpin. This is why your front door stays locked even when no one is touching it!