How many versions of iPhones are there?

Six.

iphone - The first iphone Apple created.

iphone 3G - The second iphone, improved size and look.

iphone 3G S - The third iphone, introduced video camera.

iphone 4 - The fourth iphone, slimmer, introduced video calls (FaceTime), folders, multi tasking and other features.

iphone 4S - an improved iphone 4 with new features, such as personal assistant, Siri and a better camera.

iphone 5 - a thinner, taller iphone with better cameras and includes the new lightning charger.