A key is a tool that is used to open or close a lock (lock or unlock it). A typical key consists of two parts: the blade, which is slid into a lock and is different in each key, and the bow, which the user holds to apply force. Each lock requires a unique key, you cannot insert one key in different locks. A key can be assumed as a security token which is used to access secured areas; a person having the right key for the lock can open it and gain access. Keys is an inexpensive, but not perfect, way of gaining access of physical properties like vehicles, buildings and cupboards or cabinets. Keys are an important requirement of contemporary living, and are extensively used around the world.