the key is a tool made of metal to open and lock the door by putting it into the hole in the door. The key shapes vary according to the master key form that is on the door. The keys generally consist of two parts, parent and key. The parent lock serves to unite or associate two parts, such as the door or the frame so it can not be opened without a special tool. This special instrument opening and pindu fastener is called a key. But there are also key types, such as locks that can be buttoned without a key, and the key is required to unlock them. 
[1] All keys have latches [2] that prevent open doors. The bundle stays locked when its partner's key is not used to unlock it. 
The latch inside the master key can be unlocked when the lever can be rotated [3]
Locks made of wood have been used since 4000 years ago in Ancient Egypt. It is said that the key was discovered by Theodoros of Samos in the early 6th century BC.