Before reading this book my understanding of HTML was very limited, however now I can understand the structure of a HTML page, I can see what its meant to do and how it is doing it.
Prior to reading the book, my web design was all done via FrontPage, I ignored the HTML code. This of course resulted in larger file sizes due to the software adding extra code.
Now I've learned to read and use HTML, and most importantly for myself, the book has introduced Cascading Style Sheets to me. This has enabled me to go through each of the pages on my website, rewriting the code, implementing CSS and so far, the size of the first 7 pages I have changed has reduced from a total of 103kb to 30kb.
This really is an excellent book, it starts with the basics, and provides easy to follow instructions and example HTML code.
If your wanting to learn HTML then I would highly recommend this book. Great to read through and an excellent reference tool.