There are five generations of the iPad. The first generation established design precedents, such as screen size and button placement, that have persisted through all models. The iPad 2 added a dual core Apple A5 processor and VGA front-facing and 720p rear-facing cameras designed for FaceTime video calling. The third generation added a Retina display, the new Apple A5X processor with a quad-core graphics processor, a 5 megapixel camera, HD 1080p video recording, voice dictation, and 4G (LTE).
The fourth generation adds the Apple A6X processor and replaces the 30-pin connector with an all-digital Lightning connector. The iPad Mini features a reduced screen size of 7.9 inches