The document provides an introduction and overview of using XSLT (eXtensible Stylesheet Language Transformations) with PHP4 to transform XML documents. It discusses XML basics, introduces XSLT and provides examples of using PHP's XSLT functions to apply XSL stylesheets to XML documents. It also covers more advanced XSLT topics like templates, location paths, control elements, and discusses some drawbacks of using XSLT.