Any device or system that selectively allows entry by certain persons to an area while excluding others. Usually, this term is not used to refer to ordinary key-operated locks but rather to push-button, card access, or biometric systems. This can be anything from a simple mechanical push-button lock to retinal scanners, palm scanners or badge readers wired to magnetic or electrical locking devices.

hardware device that detects the presence of electronic cards. Devices have sensors, which detect the cards, and a card reader interface, which decodes the card's electronic data and transmits that information to the device. The devices also detect state changes for doors and monitor points.

a piece of network equipment typically installed in a commercial hot spot location between one or more APs and the router that connects back to the Internet