HTML stands for Hyper Text Markup Language. It is normally used for creating web pages, and has several subgroups, ie. HTML5 and XHTML. HTML is the basis of the Wiki Markup Language (WML), and so it is easy to pick up wiki coding if you are good with HTML. HTML is also compatible with languages that improve site interactivity, such as Javascript and Java. If you are interested in learning more about HTML, you can look to the forums.

HTML is not considered a programming language. It is referred to as a 'markup language'. This is because HTML adds structure and contect to pieces of text, whereas a programming language allows you to describe some sort of process of doing something.