Card access systems works in a relationship between a plastic card and an electronic access control locks. Depending on the system, the card may contain a coded magnetic stripe that needs to be swiped into the card reader or metallic engraving that are used to trigger magnets inside the device, or even RFID technology. RFID cards function in the similar pattern except in this case, the card is brought into close proximity to a sensor. At this time, the reader, creates an electromagnetic field that is able to transmit its number or code to the reader through electronic circuit to the access control panel, which verifies if the number or code matches an approved number in the database. If the card is valid, access is granted, the door is unlocked for a short time and the entry or exit is recorded. If access is denied, the door remains locked and if someone attempts access, it gets recorded. The system also monitors the door and alarms if a door is forced open or held open for a long time after being unlocked. Each card is coded to respond to a particular card reader, a lock or a set of locks and an individual card is programmed by a computer with a unique electronic signature.