Padlock

A portable lock with a U-shaped shackle that closes through or around an object and is secured by a key or combination.

Pin tumbler lock: A lock that opens when a key aligns spring-loaded pin pairs at a shear line. Many keyed padlocks use pin tumblers to keep the plug from turning until the correct key is inserted.
Lock and key: A security system in which a lock permits access when operated by a matching key or other authorized means. Padlocks are portable examples of the broader lock-and-key system.
Hasp: A hinged fastening with a slotted plate that can be secured by a padlock. A hasp provides a fixed attachment point for a padlock on doors, gates, and boxes.
Deadbolt: A door lock whose solid bolt moves into a strike plate without a spring-latch bevel. Unlike a padlock, a deadbolt is mounted to a door and locks it to its frame.
Warded lock: A lock that blocks incorrect keys with fixed obstructions inside its keyway. Some padlocks use wards instead of movable pin mechanisms to control key access.
Keyway: The opening and internal profile through which a key enters a lock. A padlock's keyway constrains which keys can operate its cylinder.
Bicycle lock: A portable security device designed to deter theft of a bicycle by fastening it to an object. Some bicycle locks use a padlock to close a chain or cable around the frame and an anchor.
Combination lock: A lock opened by entering a sequence of symbols or numbers rather than using a key. This is a common keyless padlock type, but the broader design also includes keyed padlocks.
Shackle: The U-shaped or looped bar that passes through an object and is held by a lock body. Its shape and engagement with the body determine how the padlock attaches and releases.
Cylinder lock: A lock mechanism in which a rotating plug turns within a housing when the correct key is used. Many keyed padlocks place a cylinder in the lock body to control the shackle.

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