The iPhone was originally announced on January 9, 2007, and released on June 29, 2007. The original iPhone had no support for apps, but Apple encouraged developers to write web-based apps for the iPhone. The App Store, which allows developers to write native apps for the iPhone, was not announced until the release of the iPhone 3G/iPhone OS 2.2.1 in 2008.
The iPhone 3G was announced about a year later, and added the App Store, an electronic app distribution service, GPS, a redesigned body, a faster processor, more RAM, and 3G wireless capabilities.
The iPhone 3GS added a 3.0 megapixel camera (up from 2.0 megapixels), which was capable of shooting video and taking still pictures (the original iPhone could only take still pictures). As well as this, Voice Control was added and the RAM and processor were also bumped up.
The iPhone 4, released in 2010, was upgraded to an A4 processor, a front facing .3 megapixel camera and a back facing 5.0 megapixel camera. A CDMA iPhone 4 also was released in February 2011, for Verizon Wireless. The iPhone 4 also came with the Retina Display, a 316ppi display with eye-popping color.
The iPhone 4S was released in October 2011. Apple added a new voice assistant called Siri.
The iPhone 4S also packed an A5 processor, an 8.0 megapixel back-facing camera, and a .3 megapixel front-facing camera. The 4S was also released to Sprint and C Spire.
The iPhone 5 released in September 21, 2012. It is slimmer, lighter with 4-inch 16:9 screen. Although the screen is technically higher-res, it is of the same ppi (316). The phone also includes a custom-designed ARMv7 processor called the Apple A6.