iOS 2, originally known as iPhone OS 2, was the second major release of Apple's mobile operating system. It was launched on July 11, 2008, alongside the iPhone 3G. The reason it was called iOS 2 is that it was the successor to iPhone OS 1 and marked a major step forward by introducing the App Store, which allowed the official use of third-party apps on iPhones and iPod Touches for the first time. Before iOS 2, there was no official way to install apps outside of jailbreaking. iOS 2 also brought several new features such as push email support with Microsoft Exchange, improvements to the Mail and Calendar apps, parental controls, a scientific calculator mode, and support for WPA2 Wi-Fi security among others. This version laid the foundation for expanding iPhone from a phone and iPod to a versatile computing platform through apps which was a key reason for the operating system's naming progression from 1 to 2.