Key (lock)

A key is like a code that opens a door (or loc). When you put the key into the lock, it will open. The key has ridges on it that fit into slots in the lock. The way the ridges fit together is like a puzzle, and the code is very specific so that no other key will work! You can get new keys if you ever lose the old one, but you have to find the right code to open the door.