Wi-Fi is a technology that allows you to wirelessly connect to a local-area network. A Wi-Fi connection will allow you to browse the Internet, connect to the App Store and iTunes Store, and use many other features of your iPhone, iPad, or iPod touch. There are multiple ways one can configure a Wi-Fi network; you can connect to a network, a password-protected network, or a hidden network.
To connect to a Wi-Fi network, follow the steps on Apple Support.
To connect to a Wi-Fi network on Android, follow this article