XML
Description
A.k.a Extensible Markup Language
XML is a general markup language used to hierarchically structure data. It's not a single language in particular, but more a set of rules to describe other languages. HTML and SVG are based on XML.
Example
<?xml version="1.0" encoding="UTF-8"?>
<note>
<to>Students</to>
<from>Fabian</from>
<heading>Reminder</heading>
<body>Stay hydrated!</body>
</note>