The Apple Watch requires an iPhone to set up and activate initially, but it can perform a variety of functions without being connected to an iPhone, depending on the specific model and features.

Here are some things an Apple Watch can do without an iPhone:

1. Track fitness and activity: The Apple Watch has built-in sensors that allow it to track your heart rate, steps taken, calories burned, and other fitness metrics, which you can view and track without an iPhone.
2. Play music: If you have music stored on your Apple Watch or have a subscription to Apple Music, you can listen to music on the watch without needing an iPhone.
3. Use Siri: You can use Siri on your Apple Watch to set reminders, send messages, make phone calls, and more, without needing your iPhone nearby.
4. Use apps: Many third-party apps on the Apple Watch are designed to work independently of the iPhone, such as weather apps, news apps, and productivity apps.
5. Make phone calls: If you have a cellular-enabled Apple Watch, you can make phone calls directly from the watch without needing your iPhone.
6. Pay with Apple Pay: If you have Apple Pay set up on your Apple Watch, you can use it to make purchases without needing your iPhone.

Note that some features, such as messaging and receiving phone calls, may require a cellular-enabled Apple Watch, while other features may be limited or unavailable without an iPhone connection.