We've seen a lot of theory in this chapter, so I'm going to spend the rest of this chapter taking a look at how XML is used today in the real world. The world of XML is huge these days; in fact, XML is now used internally even in Netscape and Microsoft products, as well as installations of programming languages such as Perl. You can find a good list of organizations that produce their own XML-based languages at www.xml.org/xml/marketplace_company.jsp.
It's useful and encouraging to see how XML is being used today in these XML-based languages. Here's a new piece of terminology: As you know, XML is a metamarkup language, so it's actually used to create languages. The languages so created are applications of XML; as a result,