The Apple Watch uses Wi-Fi and GPS from your iPhone, in addition to its own accelerometer, gyroscope, heart rate and barometer sensors, to track your physical activity and movement. Now, there's been a lot of commotion regarding whether or not the wrist-worn gizmo can operate independently as a fitness tracker.
As first noted by MacObserver, American model and activist Christy Turlington-Burns, who blogs about the Apple Watch on Apple's website, said in her most recent blog entry that the device can learn about the user's stride enough over time to start accurately track workouts without an iPhone.