[Q] How to access the internal storage of other application?

Hello, I am developing an application and I wonder if it is possible to access the internal storage of other applications, know that it is possible to access the internal storage of standard applications such as photos, documents, etc.
But I wonder if it is possible to access the internal storage of all applications, not just the standards. If possible, how I do it?

Sorry for my bad English, I am Brazilian :D.