What is HTML?
HyperText Markup Language. A markup language based on but simpler than SGML used to annotate hypertext documents for publication on the World Wide Web, to take advantage of the WWW's capacity to connect documents and sectins of documents across the Net.

Here are some great HTML references:

http://www.w3schools.com
http://www.w3.org/MarkUp/Guide/
http://www.davesite.com/webstation/html/
http://www.htmlgoodies.com/tutorials/getting_started/