iPad ( ) is an iOS-based line of tablet computers designed and marketed by Apple Inc. The first iPad was released on April 3, 2010; the most recent iPad models are the iPad Air 2, released on October 22, 2014, the iPad Mini 4, released on September 9, 2015, and the iPad Pro, released on November 11, 2015. The user interface is built around the device's multi-touch screen, including a virtual keyboard. The iPad includes built-in Wi-Fi and cellular connectivity on select models. As of January 2015, there have been over 250 million iPads sold. iPad tablets are second most popular, by sales, against Android-based ones, since 2013, when Android tablet sales increased by 127%.