IPhone 3GS

iPhone 3GS is the third generation of iPhone, releasing on June 8, 2009. This would be the first iPhone to focus on the internals, where the "S" stands for speed. This device was considered to be the fastest in an iPhone for its time. This device also came with iPhoneOS 3 (now called iOS).

Another major feature was a higher megapixel count on the back camera, jumping 1 megapixel from the already 2 megapixel iPhone 3G camera. This is also the first iPhone to release with more than one camera.

Source(s): https://en.wikipedia.org/wiki/IPhone_3GS