ATracks records location, elevation, and step data for your outdoor activities. Data is stored locally so that youll always have it, and data is synched to other devices with the same Apple ID so you can view your excursions on larger screens.
Your data is stored in your own private iCloud account, and no one without access to your Apple ID can access that data.
Step data is obtained from the Apple Health app, and is only recorded on an iPhone, iPod Touch, or Apple Watch. Step data is only imported into ATracks while ATracks is actively running on an iPhone or iPod Touch.