Lock picking is the skill of unlocking a lock by analyzing and manipulating the components of the lock device, without the original key. Although lock picking can be associated with criminal intent, it is an essential skill for alocksmith. Lock picking is the ideal way of opening a lock without the correct key, while not damaging the lock, allowing it to be rekeyed for later use, which is especially important with antique locks that would be impossible to replace if destructive entry methods were used.

Lock picking is only made possible by unavoidable mechanical machining errors in the fabrication of locks.

The move towards combination locks for high security items such as safes was intended to remove the weakest part of the lock: its keyhole.

In normal situations it is almost always easier to gain access by some means other than lock picking; most common locks can be quickly and easily opened using a drill, bolt cutters, padlock shim, a bump key or a hydraulic jack. The hasp, door, or fixture they are attached to can be cut, broken, unscrewed or otherwise removed, windows can be broken etc. Therefore a lock that offers high resistance to picking does not necessarily make unauthorized access more difficult, but will make surreptitious unauthorized access more difficult. Locks are often used in combination with alarms to provide layered security.