Personally, I wouldn't worry about directories or code layout; focus instead of functionality/use cases. When I've had to do this, I usually try a dual approac

Personally, I wouldn't worry about directories or code layout; focus instead of functionality/use cases. When I've had to do this, I usually try a dual approach: - Reading code, by identifying an interesting function / use case and tracing the code (reading + stepping through debugger) from the top to the bottom. Example: start with a webpage / api and drill down to see how it works. - Adding features / fixing bugs: Once I've got a basic idea of the code layout, having to try and and do small bug fixes or small features is a great way to learn more about the system. I've never had any problem with using chat to talk with the original developers; that's what I do most of the time, and several times have had to write some initial "get started"-kind of docs for new developers coming into the project. It's something to ask for; can't hurt.