watchOS is the operating system of the Apple Watch, developed by Apple Inc. It is based on iOS, the operating system used by the iPhone, and has many similar features.[5] It was released on April 24, 2015, along with the Apple Watch, the only device that runs watchOS. watchOS exposes an API called WatchKit for developer use.
The second version, watchOS 2, included support for native third-party apps and other improvements, and was released on September 21, 2015.[6][7][8] The third version, watchOS 3, was released on September 13, 2016, to emphasize better performance and include new watch faces and stock apps. The fourth version, watchOS 4, was released on September 19, 2017. The fifth version, watchOS 5, was released on September 17, 2018,[9] to add more third-party support and new workouts, along with the "Walkie-Talkie" feature.[10] The sixth version, watchOS 6, was released on September 19, 2019.[11] The seventh version, watchOS 7, was released on September 16, 2020, to support handwashing and sleep tracking.[12][13] The eighth version, watchOS 8, was released on September 20, 2021, with updates in health monitoring, visuals, and apps.[14] The ninth version, watchOS 9, was released on September 12, 2022. The tenth version, watchOS 10, was released on September 18, 2023. The 11th version, watchOS 11, was released on September 16, 2024.