Proofreading

Proofreading is the last thing that happens before a book goes to press, and it is the only stage that looks at the book as an object rather than as a text.

The proofreader works on the typeset pages, not the manuscript. That matters, because typesetting introduces its own errors: a heading orphaned at the foot of a page, a widow line carried alone to the next, a hyphenation break that splits a word absurdly, running heads that still say the previous chapter's title, page numbers that skip, a caption misaligned with its image, an entry in the table of contents pointing at the wrong page.

They also catch what survived the edit. However good a copyedit is, a small number of errors always slip through — the eye reads what it expects. A fresh reader working slowly on paper-like proofs finds them.

Corrections come back marked on the PDF and are applied by the typesetter, then checked again. Two things are worth being honest about: no proofread catches literally every error in a full-length book, and any changes you make after the proofread need re-checking, because new text introduces new errors.