Markup Languages

A markup language is
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.

Taxonomy of Markup

There are three categories of electronic markup: presentational, procedural, and descriptive (Coombs et al., 1987):
(Source: Coombs et al., 1987)