Access control is a security measure that regulates who or what can view or use resources in a computing environment. It is used to prevent unauthorized access to confidential data, networks, and systems. Access control is an important component of any security system and is used to protect physical and digital assets. Access control systems can be as simple as a single lock and key, or as complex as an electronic system with multiple layers of authentication. Access control systems are used to restrict access to areas and resources, such as computers, networks, files, and other sensitive information. They can also be used to monitor and control user activity, such as logging in and out of systems, setting user privileges, and tracking user activity. Access control systems can be used to limit access to certain areas, such as a restricted area of a building, or to certain resources, such as a computer system. Access control systems can also be used to grant or deny access to certain users, such as allowing only certain users to access a specific file or application. Access control systems are used to protect data and resources from unauthorized access, and to ensure that only authorized users have access to the resources they need.