Why you need an editor

All writing benefits from editing and proofreading, even the editor's. Many writers are skilled at using spelling and grammar checkers, but writing and editing are very different skills. A writer or author may know what she wants to say; an editor knows how to clearly communicate the ideas and persuade the target audience.

High-level scan (substantive edit): A professional editor keeps a writer's intentions intact while ensuring a clear and appropriate voice. The editor also checks that chapters, headings, and paragraphs are ordered and formatted in a logical sequence and that all quotes and illustrations are credited and referenced.

Line read and proof: Copyeditors and proofreaders are trained to check facts and spot grammar, spelling, and other language usage errors. At these levels, the editor also points out omissions and inconsistencies that can detract from the perceived quality of a work.