The key serves as a security token for access to the locked area; locks are meant to only allow persons having the correct key to open it and gain access. In more complex mechanical lock/key systems, two different keys, one of which is known as the master key, serve to open the lock.

To make a new key for an existing lock, you cut a series of notches in the key so that it raises each of the upper pins just above the shear line. Essentially, you cut a pattern in the metal that matches the pattern of the pins in the lock.

The blade is the specific part of the key which slides inside the lock. The bow is the portion which protrudes from the blade; the part you hold in your hand when you use the key. *Some of the keyways offered. A Kwikset keys, for example, will always fit in a Kwikset lock, even if it won't turn.