Technically, proofreading happens after a book is formatted, and it’s the final step before you hit that ‘publish’ button.
This is the very last round, reading the proofs (or galleys) with the book in its bookish state. Whether you’re contracting before or after the galleys, the goal is the same. We’re looking for any typo that valiantly made it past the copyediting* stage. 
Hate proofing? I’m on it!


(Easy Math for Writers: $150 per 50K words)

*looking for a copyedit instead? You want this page.