It's what the "ML" stands for in HTML, used for creating Internet documents
[DOC] [TLE] Semantic Content Markup | Web Style Guide 3 [PAR] From its earliest origins, html was designed to distinguish clearly between a ... 
when standard html tags are used to convey meaning and content structure, not 
simply to ... with non-html web markup standards such as Mathml for scientific 
documents, ... JavaScript is a language commonly used to create interactive 
behaviors.