Google Fit is a platform that allows developers to manage user fitness data effectively. Developers, on behalf of users, can upload, download, and persist their fitness data to a central repository in the cloud. This fitness data can range from simple height and weight numbers to individual step information. The fitness data can come from various data sources, such as fitness apps, Android sensors, Android wear sensors or any other device that can connect and upload data to the Google Fit platform. The data sources can be present either locally on the phone or can be in remote devices in the form of any app or hardware sensors. This fitness data management is done using three key components, as shown in the following diagram: the first is the Google Fitness Store, which resides in the cloud; the second are web-based REST APIs; and the third are Android Fitness APIs which are on the Android devices. Now let's discuss each one of them separately in detail.
