People often confuse copy editing with proofreading. They are similar, but, in general, a copy edit is more involved. A copy editor considers the language’s syntax (grammar, punctuation, word choice) etc., and makes sure that your style sheet is applied correctly (more on a style sheet in the next post.) Additionally, anything missed at the line editing stage may be identified. They are the last checking point for general editing and fact-checking. You don’t pay a copy editor as much as a line editor because they should be doing less work.
A copy editor is not paid to point out flaws in your plot or suggest major changes to the flow of text, but they may identify and highlight smaller issues. If your work has not been professionally line-edited prior to copy editing, a copy editor may find many errors and suggest a revision to their invoice.
Remember, you pay for what you get. If you need a cheaper copy editor, try and find someone starting out, they are looking for experience and to build their portfolio. And now we had best stop procrastinating and get on with some copy editing of our own.