A pin tumbler is a type of locking mechanism commonly used in locks, such as door locks and padlocks. It consists of a cylinder that contains a series of pins of varying lengths. When the correct key is inserted, the pins align at a specific height, allowing the cylinder to turn and unlock the mechanism. This design is widely used due to its simplicity and effectiveness. The key has grooves that correspond to the lengths of the pins, ensuring that only the correct key can unlock the lock. This system enhances security by making it difficult for unauthorized individuals to open the lock without the proper key.