Lock picking is the art of opening a lock without the key and without damaging or destroying the lock or its door. It is usually used by locksmiths to let people back in who have lost their keys or locked them inside a car or house. Lock picking is very rarely used by criminals, because picking a lock is difficult and other ways of entering such as breaking a window are much easier. Some people pick their own locks as a hobby. In most places picking locks that you own is legal, but it is illegal to pick locks that you do not own or do not have permission to pick.