Some Copyediting Terms
Copyediting is correcting a manuscript from the author. Proofreading is correcting a print-ready document from the publisher. Although the handwritten symbols used to perform copyediting and proofreading are the same, they are used differently and the tasks of the copyeditor are more complicated than those of the proofreader. Frequently, people without training use the word proofreading to refer to a light edit (correcting only basic errors) and copyediting to refer to a heavy edit (improving a manuscript's clarity and logic). Although these are not the strict meaning of the terms, it is true that proofreading is usually less intensive and takes less skill than copyediting. For instance, many beginners start as proofreaders and only later move on to copyediting.
There are four kinds of copyediting: technical editing, style editing, correlation editing, and substantive editing. Each of these is described below.
     Technical editing involves such things as correcting misspellings, problems with subject-verb agreement, incorrect verb tense, unnecessary or missing commas, unmarked em-dashes and en-dashes, dangling or misplaced modifiers, problems with pronoun-antecedent agreement, misused words (e.g., effect for affect), split or fused sentences, sentence fragments, faulty attempts at parallel construction, figures that don't total in charts and tables, incorrect dates, and omitted or repeated words.
     Style editing involves standardizing a text according to a particular style. There are four main manuals of style: The Chicago Manual of Style (for most academic texts), the Publication Manual of the American Psychological Association (mostly for the social sciences), the Modern Language Association Style Manual (mostly for literary criticism), and the Associated Press Stylebook (for newspapers). These manuals are used for guidance in matters where there is no right or wrong, yet material must appear consistently. This includes standardizing words in heads, titles in bibliographies, use of single or double quote marks, serial commas, numbers, acronyms, compound words, extracts, italics, note numbers, documentation style, references style, and illustrations.
      Correlation editing involves checking related parts of the manuscript against each other. This is an extremely important step in academic copyediting and a frequently overlooked one. Since novels or newspapers do not have many related parts, copyeditors who work in these fields frequently do not learn this copyediting task. Copyeditors of academic articles or books, which have many related parts, must do crosschecks. Correlation editing includes checking cross-references to pages, tables or charts, maps, captions, endnotes, subheads, as well as checking all citations in the text with those in the references, and all titles and authors with those in the table of contents.
     Substantive editing (sometimes called content editing) involves improving logic and clarity and addressing larger problems of structure and organization. This includes replacing passive voice with active voice, varying unintentionally repeated verbs, adding dashes or parentheses to clarify subordinate material, reducing strings of adjectives or doublings, replacing indefinite pronouns with clear noun subjects, reducing the use of an author's pet word or phrase, changing words with racist and sexist connotations, defining special terms on first appearance, cutting wordy sentences, making parallel ideas appear in parallel forms, straightening out logic and connections, noting awkward phrasing that could be improved, adding transitions to improve the flow of argument, deleting irrelevant material or putting it in the footnotes, moving incorrectly placed paragraphs, deleting repeated paragraphs, providing subheads, cutting excessively long footnotes, lengthening or shortening titles for clarity, suggesting areas for additional citation or research, suggesting additional illustrations, as well as noting the absence of a real introduction or conclusion, where a title does not match content, where the argument is tangled or absent, where the argument could be made stronger with additional proofs, and where citations appear without sources.
      Layout preparation involves marking or coding the manuscript for the layout artist, so that it is clear which parts of the text are heads, tables, footnote references, and so on, so that they can be prepared for design. This includes marking or coding heads; subheads; references in the text to tables, charts, figures, maps, appendixes, and footnotes; dashes, both en and em; ellipses; and specifying the placement of tables and illustrations.
    Permissions involves asking for permission to reprint tables, charts, graphs, and illustrations that have previously appeared in print. If the manuscript contains lengthy quotations from a published work that is still under copyright, the copyeditor is expected to remind the author to obtain permission to reprint the quotations. Special rules pertain to the reproduction of unpublished materials (e.g., diaries, letters).

If you need to find a freelance copyeditor, please see my copyediting home page. I no longer copyedit myself nor do I answer email queries about copyediting.