The iPhone 4 is a touchscreen slate smartphone developed by Apple Inc. It is the fourth generation iPhone, and successor to the iPhone 3GS. It is particularly marketed for video... en.wikipedia.org - Official Apple iPhone 4 Product Series Page
The iPhone 3GS (stylized iPhone 3G[S] by many blogs) is the third generation of iPhone designed and marketed by Apple Inc. It was introduced on June 8, 2009 at the WWDC 2009 which took place at the Moscone Center, San Fran... en.wikipedia.org - Official Apple iPhone 3GS Product Series Page
The iPhone 3G is the second generation of iPhone designed and marketed by Apple Inc.. It was the successor to the original iPhone, and is succeeded by the iPhone 3GS. Introduced on June 9, 2008 at the WWDC 2008... en.wikipedia.org - Official Apple iPhone 3G Product Series Page
The iPhone—retroactively labeled the original iPhone, iPhone 2G, or iPhone EDGE—was the first generation of iPhone designed and marketed by Apple Inc. and was succeeded by the iPhone 3G. It was announced on January 9, 2007... en.wikipedia.org - Official Apple iPhone Product Series Page