I am a developmental editor. That is to say, I add and improve content, adjust dialogue, help create more telling action scenes, more descriptive settings, create and add more developed characters, streamline plots in novels and screenplays. I also work on improving content and do research for non-fiction books, including memoirs, personal development books, business  books (books given to clients to explain your background and business in depth) and all kinds of topics. The quote below is for editing a full length book or screenplay and is just an estimate. There is a huge difference between something that requires a great deal of editing of this type and ones that need only a quick clearn-up here and there.