Pin tumbler locks are a common type of locking mechanism used in doors and safes. They consist of a cylinder that contains a series of pins of varying lengths. When the correct key is inserted, the pins align at the shear line, allowing the cylinder to turn and unlock the mechanism. These locks are widely used due to their simplicity and effectiveness. The design makes it difficult for unauthorized individuals to open the lock without the correct key. Variations of pin tumbler locks can be found in many everyday items, including padlocks and car doors.