Edge-cut key

An edge-cut key is a flat key with teeth of different heights cut into its edge. It is the one most people have on their key ring and the one that comes with almost every basic lock cylinder.

This is how it works: each tooth pushes a small pin inside the cylinder up to exactly the right height. When all the pins line up, the cylinder turns.

You can spot it straight away: a saw-tooth profile on one side and the other face smooth or with a groove or two. It is practical and simple, but the cylinders that use it are usually the most exposed to techniques such as lock bumping. If your front door has an old-fashioned cylinder with an edge-cut key, think about moving to a model with more protection when you change the lock cylinder.