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Key (Lock)A key is a device which is used to open a lock. It usually consists of a specially-shaped shaft of metal, with teeth and/or grooves which fit the shape of the lock and can open the correct lock by (usually) being turned in the lock housing. A wider grip is found at the top of the key to facilitate the turn. Usually, there are only a small number of keys which can operate a certain lock. In most cases, all of the keys for a lock are given to the purchaser of the lock. Duplicates of the key can then only be made if that person has access to a key or the lock. However, some manufacturers assign an identification number to each lock and key combination. Knowing the identification number of such a lock allows a duplicate key to be made at certain places. Most people in modern society use keys on a daily basis, to secure their home, their vehicle, or to access their workplace, among other uses. Those that use a number of keys will usually place them on a ring, often with other items such as key fobs. Types of keys Master Key A master key is designed to open a set of several locks. These locks also have keys which are specific to each one and cannot open any of the others in the set. Locks which have master keys have a second set of the mechanism used to open them which is identical to all of the others in the set of locks. e.g. A pin tumbler lock will have two sets of shear points. Paracentric Key A paracentric key is designed to open a paracentric lock. It is distinguishable by the contorted shape of its tooth, which protrudes past the centre vertical line of the key barrel. Patented by the Yale lock company in 1898, paracentric keys are exceptionally difficult to pick; consequently they tend to be used in high-security settings, such as prisons. Skeleton Key A skeleton key is a very simple design of key which usually has a cylindrical shaft and a single flat, rectangular tooth. As such, it is also the easiest type of key and lock to make. These locks for these keys provide minimal security and only a slight deterrence as any key with a shaft and tooth that has the same or smaller dimensions will open the lock. Many other objects which can fit into the lock may also be able to open it. Due to its limited usefulness, this type of key and lock fell out of use after more complicated types became easier to manufacture. In modern usage, it has come to describe a key, usually with minimal features, which can open all or most of a type of badly designed lock. A few car manufacturers such as Ford sell skeleton keys for some of their locks to mechanics in order to aid servicing. This practise is naturally not very publicised. Tubular Key A tubular key is one that is designed to open a tubular pin tumbler lock. It has a hollow, cylindrical shaft which is much shorter and has a larger diameter than most conventional keys. A number of grooves of varying length are cut into outer surface at the end of the shaft. These grooves are parallel to the shaft and allow the pins in the lock to slide to the end of the groove. A small tab on the outer surface of the shaft prevents the pins in the lock from pushing the key out and works with the hollow center to guide the key as it is turned. This type of key is harder to duplicate as it is less common and requires a different machine from regular keys. Keycard A keycard is an object which stores a digital key that is used to open electronic locks. It is normally a flat, rectangular piece of plastic which contains either a magnetic stripe, a bar code or an embedded microchip with electrical contacts. The keycard will either be swiped through or inserted into the lock to transmit its key to the lock. Newer keycards may use RFID technology which does not need direct contact with the lock to transmit its key. See: smartcard. Keycards are more secure and are more convenient for applications where the key must be lent out to many people, such as in a hotel. It is easy to change the key in a keycard and lock in case the current key may be compromised. They also raise privacy concerns, since they enable computer surveillance of each entry.
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