watchOS

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<div style="font: bold 2em/1.2 -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Helvetica Neue', Helvetica, Arial, sans-serif; color: var(--wiki-color);">watchOS</div>
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| colspan="2" style="padding: 0;" | ![[watchos.webp]]
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! class="ios-lab" | Developer
| class="ios-val" | [[Apple]]
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! class="ios-lab" | Based on
| class="ios-val" | [[iOS]]; [[Darwin (operating system)|Darwin]]
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! class="ios-lab" | Written in
| class="ios-val" | C, C++, Swift, Objective-C, assembly
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! class="ios-lab" | Source model
| class="ios-val" | Closed, with open-source components
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! class="ios-lab" | Initial release
| class="ios-val" | April 24, 2015 ([[watchOS 1]])
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! class="ios-lab" | Latest release
| class="ios-val" | [[watchOS 26|watchOS 26.6]]
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! class="ios-lab" | Beta release
| class="ios-val" | [[watchOS 27|watchOS 27.0]] Developer Beta
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! class="ios-lab" | Platform
| class="ios-val" | Arm (Apple Watch)
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! class="ios-lab" | Kernel
| class="ios-val" | Hybrid ([[XNU]])
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| colspan="2" style="background-color: #333; padding: 8px;" | [https://www.apple.com/watchos/ <span style="color: #fff;">Official site for watchOS</span>]
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{{watchOS Version Navbox}}

{{Current operating systems by Apple Navbox}}

'''watchOS''' is [[Apple]]'s operating system for the Apple Watch, launched with the original watch on April 24, 2015. Derived from [[iOS]] and sharing its [[Darwin (operating system)|Darwin]] foundation, it is built around the wrist's constraints — seconds-long interactions, the Digital Crown, watch faces with complications, and aggressive power management — and around the product's defining pivot from fashion accessory to health-and-fitness device.

Its architecture matured fast under pressure: [[watchOS 1]]'s phone-tethered apps were slow enough to threaten the product, [[watchOS 2]] moved apps native, and [[watchOS 3]]'s memory-resident model made them instant — the rescue that set the platform's course. Independence came in stages (cellular in [[watchOS 4]]'s era, an on-watch App Store in [[watchOS 6]], phone-less Family Setup in [[watchOS 7]]), while the health franchise compounded: heart-rate alerts, ECG and fall detection ([[watchOS 5]]), Noise and Cycle Tracking ([[watchOS 6]]), sleep ([[watchOS 7]]), Medications and AFib History ([[watchOS 9]]), Training Load and Vitals ([[watchOS 11]]).

= History =

[[watchOS 10]] rebuilt the interface around the widget Smart Stack and full-screen apps; [[watchOS 26]] (2025) brought the year-aligned numbering, Liquid Glass design, and the AI Workout Buddy coach; [[watchOS 27]] is in beta with the Siri AI generation. Each release ships in the fall alongside its iOS sibling and the year's new watches, whose sensors (ECG, temperature, blood oxygen) typically switch on through watchOS features.

= Relationship to iOS =

watchOS pairs to an iPhone for setup and sync (Family Setup excepted) and tracks iOS's release train and version numbering — including the jump from 11 to 26. Health data flows to the iPhone's Health app; notifications, calls, and Apple Pay mirror or extend the phone. This wiki's watchOS version pages document the wrist-specific layer.

= See also =

* [[iOS]] — the parent platform

{{Operating systems by Apple Navbox}}