This site uses most of the basic features of HTML, and, since it was created using text editors (largely Programmer's File Editor, written by Alan Phillips of the Lancaster University Computer Centre), the HTML source of the pages is readable. Thus, it can serve as an source of examples for an introduction to HTML.
Thus, it seemed to me that my site was an appropriate place to put a brief introductory guide to HTML. There are a considerable number of excellent HTML tutorials out there already, though, but I will content myself with following a recommendation to include a link to the official standards for the HTML language.
Also note that this introduction only describes features useful to ordinary Internet users; thus, forms have not been dealt with, and only client-side imagemaps have been described.