iOS 2, originally known as iPhone OS 2, is the second major release of Apple's mobile operating system and was introduced on July 11, 2008. It was the first version to support third-party applications through the introduction of the App Store, allowing users to purchase and download apps directly to their iPhone and iPod Touch. iOS 2 also included several new features such as enterprise email support via Microsoft Exchange ActiveSync, a redesigned Mail app with push email capabilities, a scientific calculator mode, contact search, parental controls, multiple color-coded calendars, and the ability to save images from emails or Safari. It introduced support for new languages and improved protocol support including WPA2 and 802.1X. The update was free for iPhone users but came with a fee for iPod Touch users due to accounting rules. The last version of iOS 2 was 2.2.1, and it was succeeded by iOS 3 in June 2009.

Key Features of iOS 2

• Introduction of the App Store with 500 launch apps available.
• Support for third-party applications via the iPhone SDK.
• Push email and support for Office and iWork attachments.
• Ability to create multiple calendars with color coding.
• Parental controls with passcode locks.
• Scientific calculator in landscape mode.
• Internet protocol improvements including WPA2 and 802.1X.
• Searchable contacts and importing from SIM card.
• MobileMe support and other usability improvements.

Supported Devices

• iPhone (1st generation)
• iPhone 3G
• iPod Touch (1st and 2nd generation).

This version marked a significant step in the evolution of the iOS platform by opening it up to third-party developers and expanding its feature set substantially.