A service set identifier (SSID) is a sequence of characters that uniquely names a wireless local area network (WLAN). It is advertised by the WirelessAccessPoint for a wireless LAN. An SSID is also referred to as a network name.
Each set of wireless devices communicating directly with each other is called a basic service set (BSS). Several BSSs can be joined together to form one logical WLAN segment, referred to as an extended service set (ESS).
The Service Set Identifier uniquely identifies the ESS.