XHTML pages can be read by all XML enabled devices AND while waiting for the rest of the world to upgrade to XML supported browsers, XHTML gives you the opportunity to write "well-formed" documents now, that work in all browsers and that are backward browser compatible Since 1990, HTML (or Hyper Text Markup Language) has been the language recommended for creating Web pages. And it has been very successful . But HTML has its problems. Without going into specifics, as it's not the subject of this article, HTML has become a mess. To sort this mess out, in 1999 the World Wide Web Consortium came up with XHTML. XHTML stands for eXtended Hyper Text Markup Language, and is written in a language called XML or eXtended Markup Language.
As the name implies, XHTML has the capability to be extended. You can use extra modules to do things with your pages that weren't possible with HTML. The long-term goal is that your Web pages will be able to be understood by computers as well as humans. How does this work? Allow me to explain.
You may be thinking that computers already understand Web pages because you use a computer to view them. This is true. But computers only understand how to display your pages, not what they mean. Imagine if computers did understand what Web pages meant! You could tell your computer to go and visit all of your local supermarket's Websites and report back to you on which store is the cheapest for this week's shopping. Your computer could visit the news sites around the world and bring back the latest headlines that relate to things you're interested in. The possibilities are endless.