HTML is an acronym that stands for: Hypertext Markup Language. HTML as a form of markup coding instructs Web browsers on how it should display a Web page.

HTML Means Markup Coding

The current version of HTML is HTML v. 4.0.

XHTML

What is sometimes referred to as HTML v. 5 is an extensible form of HTML called Extensible Hypertext Markup Language or simply: XHTML.

Extensible Hypertext Mark-up Language is a hybrid of XML and HTML.

While WordPress uses XHTML, HTML collectively refers to all forms of webpage markup coding.