An access control system (ACS) is a type of security that manages and controls who or what is allowed entrance to a system, environment, or facility.

It identifies entities that have access to a controlled device or facility based on the validity of their credentials.

An ACS is primarily a physical operation implemented within high security areas, such as data centers, government/military institutes and similar facilities.

Typically, an ACS manages, monitors and controls human access to the protected equipment or facility. Most ACS’s are designed to take a user provided credential as input, verify/authenticate privileges using the access control list (ACL) and grant/deny access based on the findings.

For example, using biometric security, an ACS can be used to authorize only legitimate access to a data center facility. The individual must provide his or her thumbprint, focal or vocal credentials to an ACS, which is then verified through comparison with its database, and grants access only with valid permission.