How to introduce the user to the application?

Question

Android

In many large (and not so) applications, before the work begins, the user is introduced to the available functionality. Tell us how it's done? Or maybe read an article?
I roughly imagine that it all revolves in fragments, but I don’t understand exactly how. I hope for your help)

Answer 1

check the first launch and, as you rightly said, show beautiful pictures on the fragments

Answer 2

Look at other popular similar apps and do it in a similar way