A typographical error, also known as a TYPO, is an unintentional mistake made when typing or writing. A MISPRINT is an error in printing, such as a misspelled word or incorrect punctuation. An ERRATUM is a correction to a published text, usually printed in a separate section of the publication. A clerical error is an error made by a clerk or other office worker, such as a mistake in filing or entering data into a computer system.