The iPhone 4 is a touchscreen 3G smartphone developed by Apple Inc. It is the fourth generation iPhone, and successor to the iPhone 3GS. It is particularly marketed for video calling (marketed by Apple as FaceTime), consumption of media such as books and periodicals, movies, music, and games, and for general web and e-mail access. It was announced on June 7, 2010, at the WWDC 2010 held at the Moscone Center, San Francisco, and was released on June 24, 2010, in the United States, the United Kingdom, France, Germany and Japan.
The iPhone 4 runs Apple's iOS operating system, the same operating system as used on prior iPhones, the iPad, and the iPod Touch. It is mainly controlled by a user's fingertips on the multi-touch display, which is sensitive to fingertip contact. When released the iPhone 4 used iOS 4. The latest version available is iOS 6 (September 2012).
The most noticeable difference between the iPhone 4 and its predecessors is the new design, which incorporates an uninsulated stainless steel frame that acts as the device's antenna. The internal components of the device are situated between two panels of chemically strengthened aluminosilicate glass. It has an Apple A4 processor and 512 MB of eDRAM, twice that of its predecessor and four times that of the original iPhone. Its 3.5-inch (89 mm) LED backlit liquid crystal display with a 960×640 pixel resolution is marketed as the "Retina display".