SSID is a string used to define a common roaming domain among multiple access points. Different SSIDs on APs can enable overlapping wireless networks. The SSID was thought to be a basic password without which the client could not connect to the network. However, this is easily overridden because APs broadcast the SSIDs multiple times per second and any 802.11 analysis tool such as Airmagnet, Netstumbler, or Wildpackets Airopeek can be used to read it. And, because users themselves often configure clients, this "password" is often widely known. Should you change your SSID? Absolutely. Although the SSID does not add any layer of security, it should be changed from the default value so that other people do not accidentally use your network.