Copy editing (also copy-editing or copyediting) is the editorial work that an editor does to make formatting changes and improvements to a manuscript; copy (as a noun) refers to written or typewritten text for typesetting, printing, or publication. An editor who does this is a copy editor; an organization's highest-ranking copy editor, or the supervising editor of a group of copy editors, may be known as the copy chief.

There is no universal form for the job, or for the job title; it is often written as one word (copyediting), or with a hyphen (copy-editing); the hyphenated form is especially common in Britain. Similarly, the term copy editor may be spelled either as one word, two words, or as a hyphenated compound term.

Generally, in British newspaper and magazine publishing (but not book publishing), the job is called sub-editing or revise editing (The Times).