Service Set Identifier (SSID)
An SSID (service set identifier) is the name you give your network. When you are searching for a Wi-Fi connection, the list of names that pop up on your smartphone are SSIDs.
An SSID name can be as short as you like but no longer that 32 characters. Routers and access points often come with default SSIDs, but it's a good idea to create your own.