By now, you're probably chomping at the bit to start building those rich, highly usable Ajax web applications everyone's talking about. Wouldn't it be nice if one book taught you all the Ajax techniques you need and also gave you a needed refresher on the underlying technologies? Edmond Woychowsky thought so, and he's written that book.Woychowsky starts with a quick overview of the ways web pages have been coded since time immemorial - and their limitations. Next, he explains why Ajax is different, then introduces its key concepts step-by-step, from its earliest "primordial" ancestors to its latest incarnations.Woychowsky reviews Ajax-relevant facets of HTML and XHTML, JavaScript, XML, DTDs, schemas, XML data islands, and XMLHTTP Request. Unlike many other Ajax books, this one also shows how XSLT and XPath can be used well in Ajax applications. There's also a full chapter on the cross-browser HTML Document Object Model, which lets you do magical things like update only parts of a web page.Since Ajax is based on mature, non-proprietary standards, it's easy to develop Ajax applications using open source technologies. That's Woychowsky's approach. He first explains how today's increasingly popular open-source Ajax libraries work, utilizing examples drawn upon his own homegrown client-side JavaScript library. He offers practical introductions to open source tools like Ruby on Rails. And, throughout, he relies on examples that use a wide range of open source software - from MySQL to Firefox.