HTML means Hyper Text Mark-up Language. It is the standard for World Wide Web files, i.e. what you are viewing when you are browsing the Internet with your big computer. It allows any author to make hypertext universal documents , and let a browser do the "formatting work".
Hypertext is what you're using when you press TAB in WebSurf: almost anything can be linked to anything, e.g. a PIC to an HTML file.