What is an Access Control List (ACL)?

An Access Control List (ACL) ensures that permissions are clearly defined for users or groups regarding their access to various resources within a system. It acts as a fundamental component in access control mechanisms, allowing administrators to specify who can access certain data, applications, or files, and what actions they are permitted to perform—such as read, write, or execute. This structured list enhances security by ensuring that only authorized individuals can interact with sensitive information, thereby helping to prevent unauthorized access.

The other options do not accurately capture the purpose and functionality of an ACL. While a record of unauthorized access attempts may provide insights into security breaches, it does not define actual access permissions like an ACL does. A physical barrier to entry, such as a locked door or security gate, is a tangible security measure but does not involve the systematic granting or denial of access to digital resources. Biometric data refers to physical characteristics used for identity verification and is unrelated to the concept of defining access controls. Thus, the role of an ACL as a permissions framework is essential for effective physical and digital security planning.