Access control is a security system that can be used to regulate who or what can view or use resources in a certain environment.
There are two main types of access control: physical and logical. Physical access control limits access to campuses, buildings, rooms and physical IT assets. Logical access limits connections to computer networks, system files and data.

Access control systems perform authorization identification, authentication, access approval, and accountability of entities through login credentials including passwords, personal identification number (PINs), biometric scans, and physical or electronic keys.

Identification, Authentication, and Authorization are distinct functions of Access Control Systems.