XHTML is said to be the new version of HTML (Extensible Hypertext Markup Language). It is a combination of HTML and XML. It is currently the newest language for building web pages. It became an official W3C  Recommendation on January 26, 2000.   It was created to replace HTML and prepare for future technology  providing the internet with well-formed web documents with increased extensibility and portability.

XHTML Basics

Why use XHTML when HTML works fine?

HTML does work fine for the web and for the most part the average website is not going to gain much from using XHTML. It is only better because of well formed code and will essentially allow the developer to have more control over the content in a variety of browsers and web enabled cell phones and PDA's. Many designers after working with XHTML prefer it to HTML because after you learn the basics and get used to the format it is actually easier to develop because of the cleaner code and its easier to read the mark up. Regardless if you choose to start building your webpage's with HTML or XHTML It is highly recommended that you validate your code to help keep our internet clean.