The term 'Proofer's Mark' refers to the marks made by a proofreader on a document to indicate corrections or changes that need to be made. The three most common proofer's marks are 'caret' (^), 'STET' (Latin for 'let it stand'), and 'DELE' (Latin for 'DELETE'). The caret is used to indicate where a letter, word, or phrase should be inserted, the STET is used to indicate that no change should be made, and the DELE is used to indicate that a letter, word, or phrase should be removed.