In the engaging memoir Stet: An Editor’s Life, Diana Athill provides a delightful (in its simplicity) description of what copy editors do.
I would like to reproduce it for you here (I’ve chosen to lay out each point to break up the text):
The things which had to be done for all books were simple but time-consuming and sometimes boring (what kept one going through the boring bits was liking — usually — the book for which one was doing them).
you had to check that no spelling mistakes had crept in, and make sure that if the punctuation was eccentric it was because the author wanted it that way;
you had to watch out for carelessness (perhaps an author had decided halfway through to change a character’s name from Joe to Bob: when he went back over the script to make the alteration, had he missed any ‘Joes’?).
You had to pick up errors of fact, querying ones you were doubtful about at the risk of looking silly.
If your author quoted from other writers’ work, or from a song, you had to check that he had applied for permission to do so — almost certainly he would not have done, so you would have to do it for him.
If a list of acknowledgements and/or bibliography and/or index were called for you had to see that they were done.
If the book was to be illustrated you might have to find the illustrations, and would certainly have to decide on their order and captioning, and see that they were paid for.
And if anything in the book was obscene or potentially libellous you must submit it to a lawyer, and then persuade your author to act on his advice.
Stet: An Editor’s Life, Diana Athill, Granta Publications, London, 2000, p59
This description provides a good overview of a copy editor’s responsibilities. On the publishing spectrum a work passes through the hands of an editor, copy editor and proofreader — this can be the same person, although the work will always benefit from an independent eye doing a final check.
About Diana Athill
Diana Athill (1917–) had a long career in book publishing, helping André Deutsch set up the publishing houses Allan Wingate and André Deutsch Limited. She has edited the work of many noted authors including Norman Mailer, Jack Kerouac, Philip Roth, Simone de Beauvoir, John Updike and Brian Moore.
Diana Athill has written about her life in nine memoirs, and has also authored two volumes of short stories and a novel.
Diana Athill (wikipedia)
First published 21 Mar 2013; republished 15 Jul 2016