Proofreading or Copy-editing?
The terms proofreading and editing are often used interchangeably and the distinction between them can become blurred. In traditional publishing, proofreading means the final polish before publication to catch any errors that have slipped through the earlier rounds of editing and that may have crept in during the typesetting stage. The typesetter is the person who takes the Word document and creates the final designed pages - 'proofs'. These proofs are checked for any inconsistencies in style and layout and for any errors in spelling, punctuation and grammar. This work is carried out by the proofreader. Changes are minimal because the proofs have already been created and any change to the text can have a domino effect on the layout. Any major changes should have been made at the earlier stages of editing - see my blog on the stages of editing.
In self-publishing, proofreading is sometimes requested when the author may actually be looking for more of an editing service. It may be stylistic editing that is wanted - an improvement in the flow of the sentences, for example - rather than a final polish to check for mistakes.
The important thing is that there is a clear understanding between the proofreader and client about what service is being offered. Below is a link to the PDF on the Chartered Institute of Editing and Proofreading website which contains helpful information on the differences between proofreading and copyediting.