Proofreading is a professional service wherein errors are identified and corrected, but the content of the work is not substantively changed. Grammatical, spelling and formatting errors are identified and corrected. Proofreading is a step that takes place when a draft is nearly ready for publication. It’s an opportunity for an author’s work to undergo a final check-up by a fresh set of eyes. Proofreading involves correcting, but not revising or rewriting. Any substantive changes necessary should be flagged by the proofreader and brought to the author’s attention.