When you unpair your Apple Watch from your iPhone, your iPhone automatically creates a backup of your Apple Watch. Unpairing will erase all data from your Apple Watch. If your Apple Watch is unpaired while out of range of your iPhone, the backup might not have the latest data. When you're ready, you can pair your Apple Watch again and set it up from a backup.

* If your devices use iCloud and Messages in iCloud, your iMessages and text (SMS) and multimedia (MMS) messages are automatically stored in iCloud.