Access control lists (ACLs)

ACLs define granular permissions for system resources, specifying who can access what and how.

Access Control Lists (ACLs) are fundamental security mechanisms, acting as a table of permissions attached to an object (e.g., a file, directory, or network device). Each entry in an ACL, known as an Access Control Entry (ACE), specifies a trustee (user or group) and the specific rights granted or denied (e.g., read, write, execute, delete). For instance, an NTFS ACL on a Windows server might grant 'Domain Admins' full control over a critical database file while restricting 'Marketing Users' to read-only access. This precise control prevents unauthorized access and maintains data integrity across operating systems like Windows, Linux, and network devices from Cisco to Juniper.

https://learn.microsoft.com/en-us/windows/win32/secauthz/access-control-lists