A keycard lock is a lock operated by a keycard, a flat, rectangular plastic card. The card typically, but not always, has identical dimensions to that of a credit card or American and EU driver's license. The card stores a physical or digital pattern that the door mechanism accepts before disengaging the lock. There are several common types of keycards in use, including the mechanical holecard, barcode, magnetic stripe, Wiegand wire embedded cards, smart card (embedded with a read/write electronic microchip), RFID, and NFC proximity cards. Keycards are frequently used in hotels as an alternative to mechanical keys. The first commercial use of key cards was to raise and lower the gate at automated parking lots where users paid a monthly fee. Overview Keycard systems operate by physically moving detainers in the locking mechanism with the insertion of the card, by shining LEDs through a pattern of holes in the card and detecting the result, by swiping or inserting a magnetic stripe card, or in the case of RFID or NFC cards, merely being brought into close proximity to a sensor. Keycards may also serve as ID cards, or as part of an NFC system, have the code transmitted to a mobile phone to be placed into a digital wallet system such as Apple Pay or Google Pay, negating the need for a physical keycard. Many electronic access control locks use a Wiegand interface to connect the card swipe mechanism to the rest of the electronic entry system. Newer keycard systems use radio-frequency identification (RFID) technology such as the TLJ infinity. Types of card readers Mechanical Mechanical keycard locks employ detainers which must be arranged in pre-selected positions by the key before the bolt will move. This was a mechanical type of lock operated by a plastic key card with a pattern of holes. There were 32 positions for possible hole locations, giving approximately 4.3 billion different keys. The key could easily be changed for each new guest by inserting a new key template in the lock that matched the new key. In the early 1980s, the key card lock was electrified with LEDs that detected the holes. Wiegand cards Since the keycode is permanently set into the card at manufacture by the positions of magnetic wires, Wiegand cards can't be erased by magnetic fields or reprogrammed as magnetic stripe cards can. Many electronic access control locks use a Wiegand