This chapter took you on a marathon journey that covered XML and its applications. You learned what XML is, how XML documents are formed, and how to use them in PHP. You also learned about the XML parser functions and PHP5's powerful object-oriented DOM implementation. This chapter then covered XHTML, how it benefits us, and how easy it is to use in web applications.
With this useful piece of technology in hand, in the next chapter we look at manipulating files from within PHP. Although we will use the database for most of our data-storage needs, there will likely be times when we want to be able to read and write regular disk files. We also explain how to upload files to our server in PHP and look at the security implications of this.