The rope was the earliest locking device used. This would be knotted to detect, hence the thief knot, or hamper, like the Gordian knot. We still use this approach to shut a door that does not have any locking mechanism. History is sketchy as to when the lock started. However there are a few proofs that the Egyptians, Greek and also the Romans used wooden locks and keys some 4,000 yrs ago. The first known door lock with a key is called a pin lock or pin tumbler lock. This design is the frequently used lock even now. The ancient pin lock type used wood and rope and til today homes in Puerto Rico are still employing this technique.
Due to weakness in the old design the quantity of pins was extended as well as the orientation of the pins was changed to enhance security. These changes were then the established standards of the present day pin tumbler locks. Another development came for the pin lock; the wooden pins with bronze or iron. This new design was then patented in 1805. The patented design was further refined by the father and son locksmith in the name of Linus Yale Sr. and Linus Yale Jr. The lock design of Yale's is what is recognizable today. Wafer tumbler locks are another style of door lock. This sort of lock is often used in automobiles and cabinets. Lever locks are the third most widely used. Safes and prison doors are usually made from these types of locks.
There are also mechanical and electromechanical locks. Presently there are multiple variations of the different forms of locks. Among the list of variations we have the panic bars, lock sets, lock boxes, deadbolts, mortise locks, bump-proof locks to name a few These variations are what are presently used in buildings and houses. With today's technology used in lock for the doors we have state of the art security features. Examples of which are the alarmed panic bars which are installed in the emergency exit doors. This is also already utilized in our car door alarms.
With the continued innovations of our inventors we know for sure that the door lock technology that we currently have will still be improved allowing us to sleep better knowing that we are safe and secure in our homes. We should all remember that.