Keycards are frequently used in hotels as an alternative to mechanical keys.It is a rectangular plastic card with identical dimensions (credit card size) which stores a physical or digital signature which the door mechanism accepts before disengaging the lock.

There are several popular type of keycards in use including the mechanical holecard, bar code, magnetic stripe, Wiegand wire embedded cards, smart card (embedded with a read/write electronic microchip), and RFID proximity cards.