802.1x Access Control List (ACL) is a security protocol that enables secure access to networks, devices and applications. It is used to control access by allowing or denying certain types of traffic at the user level. ACLs can be used to identify, authenticate and authorize users, allowing them access only to specific resources they are authorized to use. It helps protect against unauthorized access, data theft and malicious activity on networks. Use of 802.1x ACL provides an extra layer of protection for data and resources within a network environment.