This book is written at several different levels, from basic to advanced, because the XSLT spectrum is so broad. I try to cover as much XSLT as possible, so just about everything is here, from the introductory to advanced level. As mentioned, I assume that you have some knowledge of both XML and HTML.
Im not going to assume that you have any programming knowledge except in one chapter, Chapter 10, which is specifically designed to take advantage of what you can do with XSLT processors using Java. If you want to work through that chapter, you should have some Java programming experience.
Because there are so many uses of XSLT available today, this book uses several different software packages; all the packages I use are free to download from the Internet, and I tell you where to find them.