Apple Watch is a line of smartwatches developed by Apple Inc. It incorporates fitness tracking and health-oriented capabilities with integration with iOS and other Apple products and services. The original generation of the device is available in four variants: Apple Watch Sport, Apple Watch, Apple Watch Hermès, and Apple Watch Edition, distinguished by different combinations of cases and first or third party interchangeable bands. Apple Watch relies on a wirelessly connected iPhone to perform many of its default functions such as calling and texting. It is compatible with the iPhone 5 or later models running iOS 8.2 or later, through the use of Bluetooth. Announced by Apple CEO Tim Cook in September 2014, the device was released in April 2015.[9][10] The Apple Watch quickly became the best-selling wearable device with the supply of 4.2 million smartwatches in the second quarter of the 2015 fiscal year.[11][12] The second generation of Apple Watch released in September 2016 includes two tiers: Apple Watch Series 2 and Apple Watch Series 1