Rating: 

I'm not qualified to say if this book is definitive or not, but I found it useful and, most of all, very easy to follow. I have been working with HTML for awhile (I have the first edition of Web Design in a Nutshell) but I am not a programmer. This has been a big help in adding functionality to my company's website.

I would, however, have liked to have seen a few XHTML-specific notes. Maybe in the next version...

Cheers!