Windows 7 includes native support of Wi-Fi Protected Setup (WPS). One functionality lets you quickly and easily configure a wireless router via Windows rather than having to access the router’s interface. When you attempt to connect to an unconfigured router (such as with the default SSID and no security) that supports WPS, Windows 7 will ask if you want set it up.
If you proceed with setup, it will ask for the WPS PIN, usually printed on the router. Once the PIN is supplied, you can change the SSID and optionally customize the security settings. It will automatically configure your computer with the chosen settings. For users not running Windows 7 or WPS, it gives you the security passphrase that you can also manually enter on clients.