The term proofreading is sometimes used incorrectly to refer to copy-editing. This is a separate activity, although there is some overlap between the two. Proofreading consists of reviewing any text, either hard copy on paper or electronic copy on a computer, and checking for typos and formatting errors. This may be done either against an original document or "blind" (without checking against any other source). Many modern proofreaders are also required to take on some light copy-editing duties, such as checking for grammar and consistency issues.