iPhone is a line of smartphones designed and marketed by Apple Inc. They run Apple’s iOS mobile operating system.
The first generation iPhone was released on June 29, 2007; the most recent iPhone model is the iPhone SE, which was unveiled at a special event on March 21, 2016. The user interface is built around the device’s multi-touch screen, including a virtual keyboard.
The iPhone has Wi-Fi and can connect to cellular networks. An iPhone can shoot video (though this was not a standard feature until the iPhone 3GS), take photos, play music, send and receive email, browse the web, send and receive text messages, follow GPS navigation, record notes, perform mathematical calculations, and receive visual voicemail. Other functions—video games, reference works, social networking, etc.—can be enabled by downloading application programs (‘apps’); as of October 2013, the App Store offered more than one million apps by Apple and third parties and is ranked as the world’s largest mobile software distribution network of its kind (by number of currently available applications).
There are nine generations of iPhone models, each accompanied by one of the nine major releases of iOS. The original 1st-generation iPhone was a GSM phone and established design precedents, such as a button placement that has persisted throughout all releases and a screen size maintained for the next four iterations. The iPhone 3G added 3G cellular network capabilities and A-GPS location. The iPhone 3GS added a faster processor and a higher-resolution camera that could record video at 480p. The iPhone 4 featured a higher-resolution 960×640 “Retina Display”, a VGA front-facing camera for video calling and other apps, and a 5-megapixel rear-facing camera with 720p video capture.