Once an author has created a complete manuscript that has been corrected and checked to his or her own satisfaction it is considered good practice (some would say essential) to pass the raw manuscript (the ”copy”) to a “copy editor”.
The copy editor’s job is to make the copy ready for publication which means that the copy editor will address a number of thing including: mistakes, omissions, inconsistencies, repetitions, grammatical errors, formatting issues and legal issues. It is often necessary to refer these changes back to the author.
When ALL changes and corrections are concluded, the final manuscript is passed to a designer or typesetter who creates a fully formatted version of the document ready for publication (printed or electronic). This document is called the “proof”. The proof is passed to a “proof reader” whose job it is to spot and correct any errors.
As printing and typesetting technology has advanced the stages just described have become rather blurred. For example, many authors produce well-formatted and checked electronic files whereas in the old days most manuscripts were created in pencil or on a typewriter. The roles of the copy editor and proof reader are sometimes combined although it is always advisable to have one final proof reading check before publication.