1. Credentials: Card, Fob, Biometrics: Users are granted access based on credentials. This can involve access cards, key fobs, or biometric information such as fingerprints, providing a unique and secure identification method. 

2. Card Reader: Credential Verification: A card reader authenticates the user’s credentials. When an access card or key fob is presented, the reader verifies the information stored on the card or fob.

3. Door Controller: The door controller processes the information from the card reader, determining whether to grant or deny access based on the user’s credentials and the access control policies configured in the system.

4. Lock: Upon receiving an access approval signal from the door controller, the lock is electronically triggered to either lock or unlock the door. This can include electric strikes, magnetic locks, or other electronically controlled locking mechanisms.

5. Door Sensor: The sensor detects and reports the current status of the door – whether it is open or closed. It ensures that the system is aware of the door portion and can trigger alarms or actions accordingly.

6. Request-to-exit Sensor (REX): Placed on the inside of the secured area, the REX sensor detects when someone is leaving. It triggers the door to unlock temporarily o allow an exist without requiring additional authentication.

7. Secure Database: The secure database stores user credentials and access permissions. It is a crucial component ensuring that only authorized individuals can access specific areas.

8. User Portal: Administrators manage access control setting through a user portal. This interface allows them to add or remote users, modify access levels, and review access logs, providing centralized control and oversight.