The fourth model of Apple's smartphone, which debuted in June 2010. The primary changes are multitasking, much higher resolution (see Retina Display), larger battery, home screen folders, voice control, five-megapixel camera, thinner case and video calling. A front-facing Webcam and Apple's FaceTime app enable iPhone 4 users, 4th-generation iPod touch users and Mac users to video call each other over Wi-Fi (as of iOS 6, FaceTime over cellular was added). In addition, a single tap switches the phone from front to back camera to turn the unit into a remote video camera for the person at the other end of the call. See iPhone 4S, iPhone and Antennagate.