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Wi-Fi Protected Setup (WPS) is a network security standard that allow users to easily secure a wireless home network, and connect wireless client devices (iPads, smart phones, etc.) to it, without accessing the router configuration screens, and without the wireless network security key/passphrase/password
wps key is a button found on router and printer devices, however its not found on old model routers so you dont have to worry about it.
To connect the printer on wifi simple follow the steps as you insert the printer cd and install the printer driver on your computer you will get the option to install it on usb or wifi select wifi and complete the installation.