For those who are brand new to this Industry Here's the Definition of HTML the programming language you need to know.

Definitions of HTML on the Web:
(Hypertext Markup Language) - The coded format language used for creating hypertext documents on the World Wide Web and controlling how Web pages appear.

Definitions of XHTML on the Web:

Extensible Hypertext Markup Language - A reformulation of HTML 4.0 in XML 1.0. XHTML is a new language for building web pages that has recently been proposed as a W3C Recommendation. This proposed Recommendation caused lots of debate on account of XHTML's usage of XML namespaces.

XML is also is used for RSS feeds.

W3c
http://www.w3.org/

Hope this help anyone who was wondering what html is.

A example of Html code is here