Proofreading refers to reading a written text for errors, usually a preliminary version of a publication. Unlike editing, which has more to do with content and organization, proofreading is typically limited to checking for spelling mistakes, typographical errors, incorrect or missing punctuation, and the like. Proofreading used to be done by hand on a typed or printed manuscript, but now is often done digitally on a computer. Certain aids have been developed for proofreading texts on computers, such as spell-checks and comment functions. Some specialist terminology is still in use from the earlier days of proofreading, such as “stet” (“leave as is”, correcting an earlier edit) and “dele” (a symbol for “delete”).