SSID

The SSID, or Service Set Identifier, is the name of a wireless local area network (WLAN). It is used by client devices to identify and connect to a specific network among multiple nearby networks. In 802.11 networks, the SSID is carried in management frames and is included in beacon frames transmitted by every access point. The SSID field is a string of up to 32 bytes, allowing a range of characters; in practice, many networks use ASCII names.

A network can be configured to broadcast its SSID in beacons, making the network easily detectable by nearby devices. Some networks are configured to not broadcast the SSID (hidden networks); in that case, clients must know and specify the exact SSID when connecting. Even when not broadcast, the SSID can still be discovered via other management traffic, so hiding is not a robust security measure.

Multiple access points can share the same SSID to create an extended service set (ESS). When roaming across APs with the same SSID, devices can switch connections to the best AP, providing seamless connectivity.

Historically, ESSID is a term still seen in older documentation, but the term SSID is the standard. The SSID is not a security feature and does not by itself protect the network; security is provided by encryption protocols such as WPA2 or WPA3 and proper authentication.

In summary, the SSID is the network's name used to identify and connect to a WLAN, with a maximum length of 32 bytes, and it may be broadcast or hidden, but hiding does not guarantee privacy.