Apple Watch (stylized as WATCH) is a line of smartwatches developed, designed, and marketed 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 was available in four variants: Apple Watch Sport, Apple Watch, Apple Watch Hermès, and Apple Watch Edition; each 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 Wi-Fi or Bluetooth. Announced by Apple CEO Tim Cook in September 2014, the device was released in April 24, 2015. 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. The second generation of Apple Watch, released in September 2016, includes two tiers: Apple Watch Series 2 and Apple Watch Series 1, which includes the S1P chip, but is otherwise identical to the original. The Series 3 was announced at a presentation at Apple Park on September 12, 2017 and will be available September 22, 2017.