IPictureService

Is there some more advanced documentation about nopcommerce?
For example, I would like to know what is IPictureService but can't find any description in official documentation.
Also for most of the other classes, there is nothing in documentation. Or am I missing something?

br, Simon

Look at class implementing IPictureService.

You will discover that it allows for managing how pictures are handled :D

Yes, but you have to walk over the code.
And from the start, when you write some custom code, you even don't know that it exists, since it is not mentioned in documentation and search also returns nothing.
There are hundreds of classes which you don't know. Searching by code is very difficult.
There is no some documentation about all classes or something similar?

The developer documentation is here.
No, it does not describe every service.  Yes, the code is the best place to learn about it.  In VS, right click the class and "Find all references", and you can see how it's used in various places.