An access control card or key fob is a physical device used in conjunction with an access control system to grant or deny entry or access to specific areas or resources. They are typically used in buildings, gated communities, parking facilities, and even for computer systems. Both access control cards and key fobs contain unique identification data that corresponds to a specific user or group of users. When the card or fob is presented to a reader, the system checks this data against its database to determine if access should be granted. The main advantage of using access control cards or key fobs is enhanced security, ensuring that only authorized individuals can access certain areas. They also provide an easy way to track and monitor entry and exit events, and administrators can quickly add, modify, or remove access permissions as needed.