For questions concerning the backup made to Google servers (which you are asked for on device initialization: "Do you want to backup your data to Google?")
When you first link your device with your Google account, you are asked whether you want to backup your data to Google servers. Later, you can find the corresponding setting in Settings→Backup & Reset→Back up my data. Both deal with backing up parts of your data into the Google cloud, to be hopefully restored in cases of need.
Core questions
- What info does Google backup?
- What exactly is this App Data that is being backed up to Google?
- How to download all my apps in google play when I have flashed a new ROM?
- Does the built-in Google app data backup work?
- Does google back-up application settings?
- Is there any way to check the backup that android does?
- Where is “Back up my data” stored? Can it be edited?
- Google Backup: Multiple devices using the same account - what happens on Restore?