Ah proofreading, the finish carpentry of editing. Many authors who create their own books think they can skip it, leaving the proofreading work to a copy editor.
Pro publishers do not do it this way.
These are the kinds of things I never thought I'd care about while I was traffic director at Graphics Express in Austin in 1984. Inside that typesetting shop, though, we had a dedicated proofreader who read every bit of type that was set. The mission was, and always is, to find typos.
I have a funny story about proofreading. In a bit of maximum irony, it comes from a writing coach. In a PDF handout, the coach writes this...
“Wikipedia says copy editing is 'the process of reviewing and correcting written material to improve accuracy, readability, and fitness for its purpose, and to ensure that it is free of error, omission, inconsistency, and repetition.' "
Then she adds, "There is a great deal of overlap between this kind editing and proofreading. It would be unusual for a writer to have both a copyedit and a proofread of the same manuscript.”
I’m going to tell you there’s a typo in the coach's advice, and let you have a little sport in finding it. Hint: it’s only two letters long and is a missing word.
Just to be thorough, that coach's advice from that PDF uses two different styles of copyedit. The Chicago Manual of Style recognizes only the verb without a space between copy and edit. So copyedit, not copy edit.
And the person doing the work? They can be a copy editor, or a copyeditor, according to the Third Edition of the New Oxford American Dictionary and the British Oxford Dictionary of English. (These are the flesh and bone of Apple's Dictionary app.)
So clearly, any advice that you don’t need to get an MS both a copyedit and a proofread depends on who’s doing the proofing. It’s safe to assume the coach had her writing copyedited. Not so much for the proofreading.
With all credit to the Chicago Manual of Style, here's what the CMOS says about proofreading:
"Proofreading here ... applies to the review of the manuscript after it has been converted to a format for publication but before it is published. Usually, this format consists of the typeset and paginated pages of a book or journal article (referred to as proofs or proof and read either on paper or as PDF) or the full text of a book or journal article intended for publication in one or more electronic formats other than PDF."
Go the extra step and get your book looking professional. Even if its only format will be digital. Pro advice: have proofreading follow your copyediting. Try to get two pros here — or if you love your copy editor, give the copy a week or two to rest before that person gives you a proofread.