Saving data on the server\cloud?

Question

Android

Good day!
The question will be more theoretical than practical (but an example will not hurt).
Essence of the question:
I need your help to deal with the issue of authorization and data storage. Making authorization, for example, through Facebook is a trifle (to some extent :)). So I did authorization and I’m more interested in where to store that data (somewhere on the server (but it will take a lot of time to write it myself (or am I mistaken?)) organize that the data of a specific user is synchronized with him at the next login).
Sorry for the bad construction of the question, I can not explain easier)).
Please advise:

1. suitable theory;
   
2. examples on the basis of which this topic could be considered.
   

Answer 1

parse.com is for you

Answer 2

dropbox? Not that?