Markup languages are languages that provide an extra information about the text in order to facilitate automated processing of it, including editing and formatting for displaying or printing.

A markup language specifies groups of characters for formatting the layout, style, structural presentation of the text such as headings, paragraphs, lists etc. These special groups of characters are called tags.

An example of the most widespread and used markup language is HTML, which is used to allow documents to be displayed in web browsers.

The other most popular is XML, which is a metalanguage, but it allows the definition of a document markup language and its structure. The advantage of using XML is the facility to develop or modify the markup language with a set of rules and tags, which suit to individual requirements and needs, for example name, title, address, etc.

XML is used rather for storing structured data, than for formatting information on a page.