Suppose you have a bunch of XML data. You want to offer it up on the web and your web server happens to be the most common one, Apache. Perhaps, as Hampton points out, you want to make the data available in various transformed ways - HTML, PDF or RTF, say, as these are very common formats. Each format needs a different operator to generate its output from your XML. Well, you may be in luck. Hampton suggests adopted AxKit as a way to do all this, fully compatible with Apache.
Along the way, he offers concise ways to use XSLT, XSP, RSS and stylesheets. In other words, he gives a motivating context in which to quickly learn the rudiments of these packages. Certainly not comprehensive in each. But this can be a blessing in disguise. For example, the full expressive power of XSLT grammar can be rather daunting to master. So his book also practises an informal but useful subtheme. He gives you a pragmatic minimum acquaintance with various subsidiary packages that are not AxKit itself. A useful extra benefit of the book.