Access control is a security measure that regulates who or what can view or use resources within a computing environment or physical space. It involves identifying, authenticating, and authorizing users or devices to ensure that only permitted individuals gain access to sensitive information, systems, or locations. Effective access control minimizes the risk of unauthorized entry, data breaches, and potential damage by implementing policies, procedures, and technologies such as passwords, biometric systems, key cards, and role-based permissions. It is a critical component of overall security strategy in both physical and digital domains.