“iDevice” redirects here. For other Apple Inc. devices, see iMac and iPod. This is a list and comparison of devices designed and marketed by Apple Inc. that run a Unix-like operating system named iOS, often colloquially referred to simply as iDevices. The devices include the iPhone multimedia smartphone, the iPod Touch handheld PC which, in design, is similar to the iPhone but has no cellular radio and other cell phone hardware, and the iPad tablet computer. All three devices function as digital audio and portable media players and Internet clients. The Apple TV, which ran iOS from the second generation of hardware onwards, is a set-top box for streaming media from local sources and from certain internet services to a connected television set, and has no screen of its own. The operating system on iOS devices can be updated through iTunes, or, on iOS 5 or later, using firmware-over-the-air (OTA) updates. A major version of iOS tends to be released every time a new type of iPhone is launched, (about once a year) and is normally free, although iPod Touch users were formerly required to pay for the update. Apple upgrades its products’ hardware periodically (approximately yearly). There have been ten major releases of iPhone (original iPhone, iPhone 3G, iPhone 3GS, iPhone 4, iPhone 4S, iPhone 5, iPhone 5C, iPhone 5S, iPhone 6, and iPhone 6 Plus), five of iPod Touch (first to fifth generations), six of iPad (first generation, iPad 2, third and fourth generations, iPad Air, and iPad Air 2), and three of iPad Mini (first generation, iPad Mini 2, and iPad Mini 3).