The iPhone can execute a very large number of applications, which are divided into various categories such as games, Social Networking, reference, GPS navigation and advertising for TV shows and celebrities. There are currently four generations of iPhones available, each being released alongside a major iOS (formerly iPhone OS) update. Even tough every iPhone has a big number of improvements notices when being compared to the previous version, the first Apple iPhone, released somewhere in 2007, has secured a model.
This means that the original iPhone has features that have resisted through four generations, like the size of the 3.5 inch LCD multi touch based screen, or the button placement and alignment. The iPhone 3G brought 3G cellular phone network capabilities, and A-GPS. The third generation iPhone 3GS brought a faster proccessor, more eDRAM memory, and other speed related changes in the hardware lineup. The iPhone 3GS also added a digital compass, which could come quite in handy, and a camera with a higher resolution that can also support video recording. The last iPhone model released so far, the iPhone 4 (released on June 24, 2010) has two cameras, one on the back of the device, and one in the front, so users are able to use the new FaceTime feature. FaceTime allows two users to establish a video conference by using the frontal camera on the iPhone 4.
This connection works only through Wi-Fi and is pretty awesome if you haven't seen a member of your family for a while, or a friend. When connected to the other person's phone, you activate the frontal camera (which was built especially for the FaceTime application), which starts filming what is going to be displayed on your relative or friend's screen. The same thing will happen to you, as your screen will be totally covered by that person's face. You image will appear two, in a tiny box that you can place anywhere on the screen, and gives you an idea of how you are seen by the other person.
All iPhone models use Apple's iOS (formerly called iPhone OS) operating system. This piece of software was created based on another operating system developed by Apple, the Mac OS for Machintosh. The device's control is built around its 3.5 inch capacitive Multi-Touch screen based Liquid Crystal Display.