Pin tumbler lock in the context of "Bit (key)"

Bitting is the depth of key cuts on a cylinder key for a pin tumbler lock, often expressed as a number. Bitting also refers to the combination of key cuts on a bit key for a warded lock or lever tumbler lock.

The exact geometry of modern keys is usually described by a code system. The bitting instructs a locksmith how to cut a certain key, to replace a lost key or make an additional copy.