A hidden Wi-Fi network is one that is intentionally configured to prevent the actual SSID (Wi-Fi network name) from appearing when looking for a Wi-Fi network to join. This means that the Wi-Fi network name must be manually entered exactly as it was entered in the configuration when setting up your Wi-Fi router.
If you are unable to connect to a hidden Wi-Fi network, but you are sure that you have entered the correct password, verify that you are entering the correct SSID and password security type. Due to the nature of hidden Wi-Fi networks, your computer does not know what type of security to use for the password you enter.
When connecting to a Wi-Fi base station with a hidden SSID (Wi-Fi network name) that's configured to use WEP (TSN) authentication, be sure you have chosen WPA/WPA2 Personal from the Security menu.
If you create a closed network with an AirPort Base Station or third-party router, the name of the network remains hidden from computers scanning for wireless networks. Clients must enter the exact network name to join the network, and they may be asked to enter a password.
For more information on WEP (TSN), see: