iOS 2, originally known as iPhone OS 2, was the second major release of Apple's iOS mobile operating system. It was officially released on July 11, 2008, along with the launch of the iPhone 3G. This version introduced the App Store, enabling the official installation of third-party applications on iPhone and iPod Touch devices. It was also available as an upgrade for the first-generation iPhone and iPod Touch, though the update was free for iPhones but cost $9.95 for iPod Touch users at the time. iPhone OS 2 was succeeded by iPhone OS 3 on June 17, 2009.