iPhone
There are five generations of iPhone models, each accompanied by one of the five major releases of iOS (formerly iPhone OS). The original iPhone was a GSM phone that established design precedents like screen size and button placement that have persisted through all models. The iPhone 3G added 3G cellular network capabilities and A-GPS location. The iPhone 3GS added a compass, faster processor, and higher resolution camera, including video recording at 480p.
The iPhone 4 has a rear facing camera (720p video) and a front facing camera (at a lower resolution) for FaceTime video calling and for use in other apps like Skype. The iPhone 4 featured a higher-resolution 960x640 display; it was released on June 24, 2010. In the U.S., AT&T was the only authorized carrier until February 10, 2011, when a CDMA version of the iPhone 4 launched for Verizon. On October 4, 2011, Apple announced the iPhone 4S.[3] The iPhone 4S added a higher resolution camera (8 megapixel) with 1080p video recording, face detection, and video stabilization, a faster, dual core processor, multi-standard wireless support (allowing a single handset to operate on networks based on both GSM/UMTS and CDMA technologies), GLONASS support and a natural language voice control system called Siri.[4] It will be available in 16 GB and 32 GB, as well as a new 64 GB capacity. In the United States, it was announced that two new carriers, C Spire and Sprint, would begin carrying the iPhone 4 and iPhone 4S on October and November 2011, respectively
