A Credential Reader, also known as a Card Reader, captures an access credential's encoded data and transmits it to an Access Control Unit (ACU). The ACU then determines whether to grant or deny access based on the cardholder's access rights.
Modern Credential Readers commonly use radio frequency identification (RFID) and/or Bluetooth wireless communication technology to pass the encoded information between the access credential and the reader when they come in close proximity, which eliminates the need for any physical contact.