Other forms: keycards
A keycard is the flat rectangle of heavy plastic that you use to unlock a door. If you lose the keycard for your hotel room you can get another one at the front desk.
A keycard looks just like a credit card or library card — and like they do, it fits easily in your wallet. Most keycards store digital information that can easily be reset. When you slide a keycard into a slot in the door, a card reader automatically releases the lock. The very first keycards, invented in the 1950s, were used by monthly pass holders to raise the gates at parking garages.