802.1X is a network access control standard that provides an authentication mechanism for devices trying to connect to a local area network (LAN). It ensures that only authorized users and devices can access the network, enhancing security by preventing unauthorized access. The standard works by using an Extensible Authentication Protocol (EAP) to communicate between the device, a Network Access Server (NAS), and an Authentication Server. When a device attempts to connect, it must provide valid credentials, which are verified before granting access to the network resources.