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, the iPad Air 2 and iPad Mini 3, were revealed on October 16, 2014 and were available for pre-order on October 17. 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 June, 2014, there have been over 200 million iPads sold since its release in 2010. An iPad can shoot video, take photos, play music, and perform Internet functions such as web-browsing and emailing. Other functions—games, reference, GPS navigation, social networking, etc.—can be enabled by downloading and installing apps. As of October 2013, the App Store has more than 475,000 native apps by Apple and third parties. There have been six versions of the iPad. The first generation established design precedents, such as the 9.7-inch screen size and button placement, that have persisted through all models.