Android is a Google OS. Relying heavily on cloud services, most of which are provided by Google, Android devices inevitably leave traces on Google's servers. Extracting information from Google's servers is a great way to complement information available in the device itself. While over-the-air acquisition can be used when all other acquisition methods fail, it is not limited to acquiring Android devices. Instead, acquisition of Google Accounts can provide a much deeper insight into user activities than what's available in a single Android smartphone.
Note that not all Android devices come with Google Mobile Services; we'll discuss this in detail later on. In particular, Amazon devices (Fire tablets and Amazon Fire Phone) do not come with any Google services preinstalled. However, end users may add Google services later on.