A luggage lock is a lock used to prevent luggage from opening by accident, usually with little or no security in mind. They may be built into luggage, or may be external locks such as padlocks or lockable straps.
In the United States the Transportation Security Administration (TSA) requires access to luggage without the passenger being present; to allow travelers to lock their luggage they have accepted certain locks which they can open and relock.
Luggage locks accepted by the TSA have universal "master" keys that will open the locks. These locks use the TSA Lock system developed by Travel Sentry. Under agreement with the TSA it is Travel Sentry that sets the standards for these locks and approves each design. Every lock with the Travel Sentry identifying mark (red diamond) is accepted by the TSA and may be opened by the TSA using their master keys. Some TSA accepted luggage locks feature an indicator which will appear red if opened by a master key.