iOS 8 is the eighth major release of the iOS mobile operating system designed by Apple Inc. as the successor to iOS 7. It was announced at the company’s Worldwide Developers Conference (WWDC) 2014 on June 2, 2014, and was released on September 17, 2014. Billed as « The biggest change to iOS since the introduction of the App Store », iOS 8 builds on the major redesign that iOS 7 introduced, while including many enhancements and interface improvements. As of May 11, 2015, iOS 8 has been installed on 82% of compatible Apple devices. The latest version of the operating system is iOS 8.3, released on April 8, 2015. iOS 8.4 beta 3 was released on May 11, 2015.