What is a developmental edit?

My next novel, MERCY ROAD, will be published next year and is now entering the editing process at my publisher. The first step is done by a developmental editor, who looks primarily at the content but assesses all aspects of the novel, gives advice, and makes suggestions. You could say the developmental editor looks at the "big picture," but he or she will do some line-by-line editing, too. Even though I'm a developmental editor myself in addition to being a writer, I find this step very valuable and wouldn't want to do without it. A fresh but experienced set of eyes has always been a great help to me. After this step has been completed, the book goes to a copyeditor and then a proofreader. I'll keep you posted about all of those steps, too.