History
The term markup is derived from the traditional publishing practice of “marking up”‘ a manuscript, which involves adding handwritten annotations in the form of conventional symbolic printer’s instructions in the margins and text of a paper manuscript or printed proof. For centuries, this task was done primarily by skilled typographers known as “markup men” or “copy markers” who marked up text to indicate what typeface, style, and size should be applied to each part, and then passed the manuscript to others for typesetting by hand. Markup was also commonly applied by editors, proofreaders, publishers, and graphic designers, and indeed by document authors.