Proofreading is the very last editorial stage and is typically done on a printed and bound document. These are often called a proof, or an advanced reader copy (ARC). Sometimes when a designer does the layout for a manuscript things go missing or errors may be introduced into the document. The goal of proofreading is to ensure that these errors are caught before the book is committed to a larger print run. This stage is highly recommended for authors who are self-publishing.
What to expect from a proofread:
I will proofread a printed proof or ARC of your book, physically marking on the pages with pen. Your marked up proof will then be mailed back to you. I'll pay special attention to design elements including title pages, running headers and footers, keep an eye out for missing pages, and for spelling errors that made it into the proof.