iPhone is a product of Apple Inc. It is a line of smartphones with internet and multimedia-enabled features. It made its debut launch on 9th January 2007. It has as yet four generations. Along with them four operating systems, specifically developed for use with these iPhones, were also launched. These operating systems are referred to as iOS meaning iPhone Operating Systems.
The first generation of iPhone termed as the original had touch screen interface. Similar interface along with the button placement and screen size is maintained in new versions also. The second generation of iPhone termed as iPhone 3G has 3G cellular network capabilities and A-GPS location.
The third generation is known as iPhone 3GS and has enhanced performance capabilities and come with a high resolution camera, a compass and a high speed processor. Fourth generation, the iPhone 4, has awesome features; a high-resolution video display with a high mega pixel camera and an exciting new feature of FaceTime video calling.
All the versions of iPhone have a media player, internet facility, Wi-Fi connectivity, and visual voicemail featureing as camera phone. Apple has maintained a similar design for the interface of all its iPhone sets, with a large touch screen and a single button along with providing a virtual keyboard. The iPhone users can download different third party applications from the Apple's App Store including GPS navigation, social networking, games as well as various applications for television shows and movies etc. All of these 200,000+ apps have been approved by Apple Inc.