What is proofreading?

Proofreading is the last quality check before a book is published. Traditionally a proofreader works on the typeset pages — the proofs — rather than the manuscript, looking for errors the earlier edits missed and problems introduced in layout.

That includes remaining typos and missing words, but also things only visible on the page: wrong or missing page numbers and running heads, chapters starting on the wrong page, widows and orphans (single lines stranded at the top or bottom of a page), bad hyphenation and word breaks, inconsistent fonts or spacing, broken table of contents entries, and image or caption mistakes. For eBooks, it means checking the EPUB on more than one device or app.

Proofreading is not a substitute for editing. A proofreader should not be rewriting sentences or restructuring chapters; at this stage changes should be minimal, because every change risks new errors and can shift page breaks — and in print, a page-count change alters the spine width.

Self-publishers can proofread themselves, but it is hard to see your own mistakes. Useful techniques include reading on paper (a proof copy is ideal), reading aloud, using text-to-speech, and reading slowly from the end backwards for typos. A professional proofreader or a sharp-eyed reader with a fresh view is worth the investment for most books.