HTG Explains: What Android Data is Backed Up Automatically?
 

Much of the data on your Android phone or tablet is backed up by Google (or the individual apps you use) automatically. Your photos can also be backed up automatically, but aren’t by default. However, some data is never backed up automatically.

We’ll explain exactly what data is backed up automatically and what isn’t, so you can rest easy knowing your data is safe – or take steps to back up some application data on your own.

http://www.howtogeek.com/140376/htg-...automatically/