Restricting the ability to enter and do things in a physical or digital area is achieved through access controls.
From a cyber security standpoint, physical access control concerns restricting the ability physically access to entry points in an area that holds access to digital systems, machines and devices can include things like locks on doors and windows, air gaps, security guards and the like. It can also include ensuring recording devices cannot enter an area with a person such as glasses, pens, paper, watches, and USB sticks.
Digital access controls can include usernames and passwords, multi factor authentication, and the restricting of rights to do things with access through software access controls such as user permissions and privileges, closing ports and setting rules in Firewalls, Intrusion Detection, Intrusion Prevention, WiFi, and Antivirus systems. These digital access controls to a particular machine, device or system can be applied to people and to other systems, machines and devices.