Copy-editing
A copy-editor works to make an author's words clear, consistent, unambiguous and accurate, and at the same time marks up the manuscript for the typesetter.
Clear: the text does not ramble or jump about, and is at the right level for the intended reader.
Consistent: the structure of the text (eg into parts and chapters) is consistent, and the text is consistent in terms of spelling, caplitalisation, hyphenation and so on.
Unambiguous: the wrong meaning cannot be taken from what is written. Frequently this means ensuring correct grammar and punctuation.
Accurate: particularly for non-fiction, no obvious errors have crept into the text, for example inaccurate quotations.
Manuscript mark-up: mark up for the typesetter not only errors to be corrected but also physical attributes of the manuscript, for example its hierarchy of headings, displayed quotations, lists, or the location of footnotes and diagrams.
Proofreading
Technically, a proofreader compares a final document (usually typeset by a typesetter) against the previous version of the document (usually a document which has been copy-edited and therefore has changes marked up on it).
So technically, a proofreader has two documents, one to compare against the other. A proofreader will also look out for and correct obvious errors that might have been missed by the copy-editor; but will leave anything that is not obvious well alone - or will refer to the copy-editor, author or desk editor (or whoever is appropriate) for their attention.
To quote from the Chartered Institute of Editing and Proofreading:
‘...the proofreader reads the proof for consistency in usage and layout, for accuracy in the text and references and for typesetting errors. However, the proofreader is acting only as a quality check, making sure that the copy-editor or typesetter has not missed something. He or she is not responsible for overall consistency and accuracy.’
Nowadays, straightforward proofreading is quite rare. More and more jobs take the form of a 'blind proofread'.
Blind proofread
For a blind proofread, a proofreader works through a final document but, crucially, does not have a previous document for comparison. The proofreader is looking for obvious errors that were either missed by the copy-editor, or which were perhaps marked up by the copy-editor and either missed by the typesetter or performed inaccurately.
To quote from the Chartered Institute of Editing and Proofreading:
...the proofreader reads the proof for consistency in usage and layout, for accuracy in the text and references and for typesetting errors. However, the proofreader is acting only as a quality check, making sure that the copy-editor or typesetter has not missed something. He or she is not responsible for overall consistency and accuracy.
A blind proofread is not the same as a normal proofread, but nor is it the same as a copy-edit. It lies somewhere in between, and a proofreader and a client would need to establish the precise parameters for a blind proofread job before it was undertaken. Nowadays fewer publications go through both a copy-edit and proofread, simply because of cost, and so a blind proofread ends up acting as both.
Onscreen editing
Onscreen editing simply means making or marking up file changes onscreen and not on paper. The two most common ways of doing this are:
making changes in a word document, using 'tracked changes' to, in effect, mark up the changes to be made; and
marking up changes on a pdf document, using stamps to replicate the standard copy-editing or proofreading marks.
But there are lots of other types of onscreen editing - for example using LaTEX files, or using data pulled from a website.
Translation, transliteration and transcription
Translation means simply saying the same thing in a different language. This is not something that editors typically do. If you need something translated, you are best to find someone who specialises in translation from the Institute of Translation and Interpreting (ITI).
Transliteration is very similar to translation, except that the originating language uses a different alphabet from the target language.
Transcription means to write down spoken words. It is similar to audio dictation, except that when somebody dictates, they are doing so with the full knowledge that someone is going to have to listen to their words and write them down or type them out, and will therefore speak clearly; whereas a transcription may be made of a conversation, or an interview, or court proceedings, where the speakers are not speaking in such a way as to make life easy for the future transcriber.
In all three cases, proofreading doesn't take place, and copy-editing only to the extent that the editor might look out for factual inaccuracies and perhaps better ways of setting out whatever material is being moved from one form to another
Typesetting
Typesetting does not fall within the remit of a copy-editor or a proofreader. A typesetter takes whatever material has been copy-edited and proofread and used whatever software they use to turn it into the final product to be published. The typesetter will follow the instructions marked up by the copy-editor and proofreader, but unless something is blindingly obvious, they will not make any changes to the text other than those indicated by instructions.
There are, of course, proofreaders and copy-editors who are capable of some forms of typesetting, but in essence it is a different skill.
Indexing
It is a common misconception that an editor can index the contents of a book ‘as they go along’. No, they can’t. In fact unless they have been properly trained, they will be unable to create any sort of meaningful index.
To get a book indexed, you need to commission an indexer: it’s a completely different skill from copy-editing or proofreading. Perhaps not surprisingly, the best way to find a good indexer is to go to the directory of the Society of Indexers.
There are, of course, some editors who have also trained as indexers
Copywriting
Clients sometimes confuse copywriting with copy-editing, and yet the two skills couldn’t be more different. Artificial Intelligence currently makes a rather good definition of what copywriting is all about:
A copywriter writes persuasive and engaging content for marketing and advertising purposes, aiming to encourage a specific action from the reader, such as making a purchase, signing up for a newsletter, or visiting a website. They write for a wide variety of media, including websites, advertisements, emails, social media, brochures, and press releases, while also conducting research, editing their work, and collaborating with other teams like design and marketing. The key goal is to clearly communicate a product's or service's benefits and build a connection with the audience to achieve business objectives.
So copywriters create material; they don’t work on it once it’s been created by someone else (which is what copy-editors do). Editors don’t work as copywriters, or if they do, it’s as a completely separate line of work.
Writing, rewriting and research
Writing does not lie in the province of an editor, other than wrestling with how to best unravel some obscure text presented by a writer. Editors work on text once it has been created by a writer. They do not carry out actual writing.
Rewriting can be a grey area. On occasion a writer might ask if certain sections of text can be rewritten to help clarity. Generally speaking there is nothing wrong with that (provided the editor gets paid for what is essentially an extra service) - except if the original material forms part of a dissertation or thesis. Changing the text for a dissertation or thesis should most definitely not be on the editor’s to-do list: the work has to be seen as the student’s. For more on this issue, check out the section on theses and dissertations.
Research is also not part of an editor’s job. The writer should already have done all that before handing over the article, essay or book to an editor to work on. Sometimes an editor is asked to ‘fact check’ some material. Clealy this is a dangerous business. The editor needs to know something about whatever is being edited, and they should make it clear that, fact-checking or no fact-checking, they are not responsible for any factual errors that remain in the finished text.