An SSID is a network name, not — I repeat, not — a password. A wireless network has an SSID to distinguish it from other wireless networks in the vicinity. The SSID was never designed to be hidden, and therefore won’t provide your network with any kind of protection if you try to hide it.
Obviously feature demand drives the specifications, so even though everybody eventually supported hidden SSIDs, the point is that there’s no extra protection from hiding your SSID.
How Should You Secure Your Network Then?
When it comes to wireless network security, there’s really only one rule that you need to follow: Use WPA2 encryption, and make sure that you are using a strong network key.
If you’re not using encryption, or you’re using the pathetic WEP encryption scheme, it doesn’t matter whether you hide your SSID, filter MAC addresses, or cover your head in tin foil-your network is wide open for hacking in a matter of minutes.