XHTML

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.
 

• HTML vs XHTML
• XMLNS Declaration
• XHTML Reference Sheet

XHTML Basics

• XHTML tags are all lowercase
• XHTML is much stricter, tidier version of HTML.
• Pages written in XHTML will work well in most browsers
• All tags, including empty elements, must be closed
• XHTML is an upgrade of HTML 4.0 as an application of XML.
• The elements (tags) and attributes are almost identical to HTML

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.