ESSID

ESSID, or Extended Service Set Identifier, is the name assigned to a wireless local area network (WLAN) that uses multiple access points to form a single network. It identifies the extended service set, a collection of Basic Service Sets that share the same network name and security settings, enabling devices to roam between APs without disconnecting.

If a network includes more than one access point, each AP forms a Basic Service Set (BSS) with its own BSSID (MAC address). All BSSs that share the same ESSID belong to the same Extended Service Set and are connected through the distribution system. When a client associates with any AP in the set, it effectively remains within the same network as long as the ESSID remains the same.

SSIDs are the user-visible network names; the term ESSID is used to emphasize the extended service set concept, though in practice the two terms are often used interchangeably. Routers and access points may broadcast the ESSID to allow clients to discover the network; some devices can be configured to hide the SSID, requiring manual entry of the network name to connect.

Security is not provided by the ESSID itself. The ESSID identifies the network, but protection comes from encryption and authentication mechanisms such as WPA2 or WPA3, and from network access controls. Administrators may configure multiple APs with the same ESSID to support roaming within a single network, while using different SSIDs for separate networks, guest access, or VLAN segmentation.