A formatting language, that includes textual instructions to the formatter, intermingled with the text to be formatted. For example, HTML & LaTeX.
Plain text that is 'marked up' by additional text to add style and structure to the information. The markup is usually not shown to the reader other than through the computer's markup interpretation.
Surrounding text with beginning and ending tags, typically set off in angle brackets. This is bold. Translators must take care to leave the words in the tags alone. Translation memory tools that are markup aware (e.g., Trados TagEditor) do not change tags, except for certain quoted material inside a tag's attrributes. For example See markup languages like HTML, SGML, and XML.