Developmental edit
A developmental edit is the first and deepest stage of editing, addressing a manuscript's structure, plot, character, pacing, point of view and theme before any attention is paid to individual sentences.
The usual deliverable is a full read followed by an editorial letter — often between five and twenty-five pages — plus notes in the margins pointing to the specific places the letter is talking about.
It asks what the book is trying to do and where it is not doing it. Where the throughline goes quiet. Whether the protagonist actually causes the ending. Which subplot is competing with the main one instead of feeding it. Which character the reader is supposed to be worried about in chapter nineteen, and whether they still are.
It comes first because it makes work disappear. Polishing a chapter at sentence level and then cutting that chapter in revision is paid-for work thrown in the bin.
Expect to rewrite. A developmental edit ends with a plan, not a clean file. It is the right service when readers tell you something is wrong but cannot tell you what — or when you already know and cannot see the way out.