a kind of coding, or "tags," inserted into text that embeds details about the structure and appearance of the text with in a text file-for example, HTML. the word "markup" is derived from the traditional publishing practice of "marking up" a manuscript, that is, adding printer's instruction sin the margins of a paper manuscript. Example: SGML (important because markup languages have codes for indicating layout and styling, such as boldface, italics, paragraphs, and insertion of graphics