What is it?

The Apple Watch is a line of smartwatches developed and marketed by Apple Inc. It was first released in April 2015 and quickly became the world's best-selling wearable device. The Apple Watch combines fitness tracking, health-oriented capabilities, and wireless telecommunication, integrating with watchOS and other Apple products and services.

Each new generation is typically released in September, labeled as a 'Series' (e.g., Series 1 through Series 10, plus the Apple Watch Ultra and SE models). The watch comes in multiple variants defined by casing material, color, and size, with options for aluminum, stainless steel, titanium, and ceramic. Bands can be selected from Apple or co-branded partners like Nike and Hermès.

The Apple Watch operates in conjunction with the user's iPhone for setup and data syncing, but can connect to Wi-Fi or cellular networks (on LTE/5G models) for independent communication, app use, and audio streaming. It can make and receive phone calls without the paired iPhone nearby.

As of September 2025, new Apple Watches come with watchOS 26 preinstalled and require an iPhone running iOS 26, compatible with iPhone 11 or later. The Apple Watch is the only smartwatch fully supported for the iPhone, as Apple restricts APIs for other smartwatches, limiting their functionality.

The device has evolved from a fashion accessory to a comprehensive health and fitness tool, with features like heart rate monitoring, ECG, blood oxygen sensing, fall detection, and sleep tracking. It has also been used in medical research studies.

Key Facts

The first Apple Watch was released on April 24, 2015.
It quickly became the world's best-selling wearable device, with 4.2 million units sold in Q2 2015.
As of December 2022, over 115 million people were estimated to use an Apple Watch.
New models are typically announced in September each year, labeled as 'Series' (e.g., Series 1–10, SE, Ultra).
The watch requires an iPhone for initial setup and full functionality, but LTE/5G models can operate independently.
Key health features include heart rate monitoring, ECG, blood oxygen sensor, fall detection, and sleep tracking.
The Apple Watch is available in multiple materials: aluminum, stainless steel, titanium, and ceramic (discontinued).
Co-branded models include Apple Watch Nike+ and Apple Watch Hermès.
The watch runs watchOS, with the latest version as of 2025 being watchOS 26.
It has been used in medical research, including studies on heart health and COVID-19 detection.
The Apple Watch Ultra, introduced in 2022, is a rugged model designed for extreme sports and outdoor activities.
Battery life varies by model, typically lasting up to 18 hours on a single charge.

Full Explanation

Hardware and Design

The Apple Watch features a rectangular display with rounded corners, a digital crown for navigation, and a side button. Early models used a 38mm or 42mm case size, while later models expanded to 40mm, 44mm, 45mm, 49mm (Ultra), and 41mm, 45mm (Series 7–10). The display uses OLED technology, with always-on capability introduced in Series 5.

The watch is powered by Apple's S-series system-in-package (SiP), which includes the processor, memory, storage, and other components. The S1 chip in the original model was later upgraded to S2, S3, and so on, with the S9 SiP in Series 9 and S10 in Series 10. The Ultra models use a more powerful S8 or S9 SiP.

Sensors include an accelerometer, gyroscope, heart rate sensor (optical and electrical), barometric altimeter, compass, SpO2 sensor, and temperature sensor. The Series 4 introduced an electrical heart rate sensor for ECG, and the Series 6 added a blood oxygen sensor. The Ultra has a depth gauge and water temperature sensor for diving.

Software and watchOS

The Apple Watch runs watchOS, a derivative of iOS. The operating system features a home screen with circular app icons, customizable watch faces, and a Control Center. Apps include Phone, Messages, Mail, Maps, Music, Wallet, Activity, Workout, Heart Rate, and third-party apps.

watchOS updates are released annually alongside iOS updates. Key features include notification management, Siri integration, Apple Pay, Walkie-Talkie, and the Breathe app for mindfulness. watchOS 3 added wheelchair tracking and social sharing in Activity. Later versions added sleep tracking, handwashing detection, and low-power mode.

Health and Fitness Features

The Apple Watch is a powerful health and fitness device. It tracks daily activity through three rings: Move (active calories), Exercise (minutes of brisk activity), and Stand (hours with movement). Workout tracking supports many activities, including running, cycling, swimming, yoga, and hiking.

Health monitoring includes heart rate alerts for high/low heart rate, irregular rhythm notifications, and ECG app for atrial fibrillation detection. The blood oxygen app measures SpO2 levels. Fall detection and crash detection (Series 8 and later) can automatically call emergency services. Sleep tracking monitors sleep stages and duration.

The watch also includes cycle tracking for menstrual health, with temperature sensing for ovulation estimates. The Ultra adds a siren for emergencies and precision dual-frequency GPS for accurate location tracking.

History

Development of the Apple Watch began shortly after Steve Jobs' death in October 2011. Apple design chief Jony Ive became interested in building a watch, and by February 2013, reports confirmed Apple was working on a smartwatch with a curved display. The project was led by Kevin Lynch, former CTO of Adobe, reporting to Bob Mansfield.

The team initially struggled to define the watch's purpose, but eventually focused on reducing phone usage by providing a more human way to interact with notifications. The software underwent three major redesigns to avoid long interactions. The digital crown was developed as a physical input method, and Force Touch was added for contextual menus.

The Apple Watch was unveiled on September 9, 2014, at an event where the iPhone 6 was also presented. Tim Cook introduced it as "one more thing." Pre-orders began on April 10, 2015, with the official release on April 24, 2015. Initially, it was not available for walk-in purchases at Apple Stores, requiring online reservations.

In September 2015, Apple launched a collaboration with Hermès, offering stainless steel models with leather bands. In 2016, the Apple Watch Nike+ was introduced, featuring exclusive bands and watch faces. The Apple Watch Series 1 and Series 2 were released in 2016, with Series 2 adding GPS and water resistance. The Series 3 (2017) introduced cellular connectivity, and the Series 4 (2018) brought a larger display and ECG.

Subsequent models added always-on display (Series 5), blood oxygen sensor (Series 6), larger screen (Series 7), temperature sensor and crash detection (Series 8), and the rugged Ultra model (2022). The Apple Watch SE, a budget model, was introduced in 2020. As of 2025, the lineup includes Series 10, Ultra 3, and SE 3.

Why it matters

The Apple Watch has transformed the wearable technology market, setting the standard for smartwatches with its seamless integration with the iPhone and comprehensive health features. It has become a vital tool for health monitoring, helping users detect potential medical issues like atrial fibrillation and falls, and has been used in large-scale health studies.

The device has also influenced the design and functionality of other smartwatches, pushing competitors to improve their health sensors and software. Its success has made Apple the dominant player in the smartwatch market, with a loyal customer base that upgrades regularly.

Beyond personal use, the Apple Watch has applications in healthcare, fitness, and emergency response. Its crash detection and fall detection features have saved lives, and its health data can be shared with doctors. The watch also promotes an active lifestyle through activity rings and workout tracking.

As technology advances, the Apple Watch continues to evolve, with potential future features like non-invasive blood glucose monitoring and advanced sleep apnea detection. It remains a key part of Apple's ecosystem, driving innovation in wearable health technology.