The idea of changing the lock has come to us with ​​husband after our neighbors were robbed. We decided that our lock is obsolete, and now there are surely more sophisticated devices. It turned out that there are many different types of locks and each has its own degree of reliability. In general, lock is device for blocking. It is used for blocking doors, lids, containers, etc., as well as for locking objects to prevent their abduction. Depending on the operating principle of the drive locks distinguish mechanical and electrical. Depending on the mounting distinguish Padlocks, invoices, built-in lock and other. For the first time this device appeared in the ancient states - Assyria, Babylon and Egypt in about the 2nd millennium B.C. The design of the lock of ancient Egypt already laid the elements used in modern devices. Modern locks depending on the device and the mechanism fall into without lever, lever, cylinder, secret. Locks are removable (including hanging) or fixed, permanently installed (built-in locks, overhead). Reliability of the castle is the main requirement imposed on the device. The key is a tool used for opening locks. Picking can be carried out in different ways. Often, thieves use a system of selection keys. But if the lock is really safety, it is very difficult to make it. Material for the manufacture of keys may be metal (iron, copper, etc.), wood, and plastic. Plastic cards are the key to electronic locks. The first keys as locks appeared simultaneously with the first civilizations. The first mention of them exists in the myths and the Old Testament. In the tomb of Pharaoh Ramses II, the historians found a wooden key.