The first key operated lock was invented in ancient Egypt about 2000 B.C. it consisted of a large wooden bolt that was fastened to the outside of a gate. Pegs called pins were inserted into the holes and prevented it from being moved. A key raised the pins so the bolt could be moved thus opening the gate. Later locks were developed according to three basic principles – the warded principle, the lever principle and the pin-tumbler principle. The ancient Romans invented the warded principle. The key had to pas a series of wards (obstacles) in order to unlock the bolt.

Warded locks were the most commonly used until the mid-1800, and some are still used today. The lever principle was developed in the late 1700′s. Lever locks have one or, more levers in their mechanism. The lever must be raised to a specific height before the bolt can be removed. Only the correct key can raise the levers to precisely the height needed. The modern pin-tumbler lock was invented in 1865 by an American locksmith named Linus Yale, Jr. it was based on the principle similar to that of the ancient Egyptian lock. The pin-tumbler lock is one of the most secure key-operated locks ever invented. It was also was the first lock to be mass-produced.

Electronic locks are of three basic types. These are – card or key systems, electronic combination locks and biometric entry systems. Card/key systems are the most widely used electronic lock systems. A key card is a flat rectangular piece of plastic similar to in dimensions to a credit card or drivers license. There are several type of key cards. Some of these are holecards, barcodes and magnetic stripe. The holecard is not widely used now-a-days. The magnetic stripe cards are the most widely used key cards.

Electronic combination locks or keypads as they are more commonly known use an electromagnet mounted in the door and the bolt mounted in the wall. When the door is ‘locked’ the electromagnet is activated and it holds fast to the bolt, thus locking the door. These locks require a numerical combination (key) in order to unlock them. A drawback of this technology is that person intent on entry can easily determine the key by simply viewing a couple of successful entries or trying different combinations of the worn out keys. This can be overcome by improved keypad technology or by incorporating a biometric element into the sequence.

Biometrics is study of human characteristics like fingerprints, retinas, irises and voice for unique and distinct patterns for the purposes of authentification. Formally biometric systems were used only when a high security situation was involved. Mainly government bodies and large corporations used biometric technology due to the costs involved. As time has gone by, the technology has improved and become cheaper its applications have increased. Biometrics are now becoming increasingly common in corporate security systems and consumer electronics. For example laptops come equipped with fingerprint scanners and the traditional wall safes are equipped with a combination of keypad, fingerprint and voice locks.