watchOS by Apple

watchOS is the mobile operating system of the Apple Watch, developed by Apple. Released on April 24, 2015, it is based on the iOS operating system and has many similar features. The platform's interface includes the so called Carousel home screen that is composed of circular application icons, which can be zoomed in and out with the Digital Crown and dragged and launched by touching the display. Many of the apps are miniaturized, simplified versions of their iOS counterparts. watchOS comes with a number of Apple-made apps for music playback, activity & health tracking, contactless payments (Apple Pay) and notifications. Its functionality can be extended with third party apps.