XHTML Information

All web Markup languages are based on SGML, a horrendously complicated language that is not designed for humans to write. SGML is what is called a metalanguage; that is, a language that is used to define other languages. To make its power available to web developers, SGML was used to create XML (eXtensible Markup Language), a simplified version, and also a metalanguage.

XML is a powerful format — you create your own tags and attributes to suit the type of document you're writing. By using a set group of tags and attributes and following the rules of XML, you've created a new Markup language.

This is what has been done to create XHTML (eXtensible HyperText Markup Language) — which is why you'll see XHTML being called a subset or application of XML. The pre-existing HTML 4.01 tags and attributes were used as the vocabulary of this new Markup language, with XML providing the rules of how they are put together.

So, using XHTML, you are really writing XML code, but restricting yourself to a predetermined set of elements. This gives you all the benefits of XML (see below), while avoiding the complications of true XML; bridging the gap for developers who might not fancy taking on something as tricky as full-on XML. As you're coding under the guise of XHTML, all of the tags available to you should be familiar. Writing XHTML requires that you follow the rules of conformant XML, such as correct syntax and structure. As XHTML looks so much like classic HTML, it faces no compatibility problems as long as some simple coding guidelines are followed.

Benefits of XHTML

The benefits of adopting XHTML now or migrating your existing site to the new standards are many. First of all, they ensure excellent forward-compatibility for your creations. XHTML is the new set of standards that the web will be built on in the years to come, so future-proofing your work early will save you much trouble later on. Future browser versions might stop supporting deprecated elements from old HTML drafts, and so many old basic-HTML sites may start displaying incorrectly and unpredictably.

Once you have used XHTML for a short time, it is no more difficult to use than HTML ever was, and in ways is easier since it is built on a more simplified set of standards. Writing code is a more streamlined experience, as gone are the days of browser hacks and display tricks. Editing your existing code is also a nicer experience as it is infinitely cleaner and more self-explanatory. Browsers can also interpret and display a clean XHTML page quicker than one with errors that the browser may have to handle.

A well-written XHTML page is more accessible than an old style HTML page, and is guaranteed to work in any >standards-compliant browser (which the latest round have finally become) due to the insistence on rules and sticking to accepted W3C specifications. As mentioned above, XHTML allows greater access to configurations other than a computer and browser. This interoperability is another aspect of XHTML's greater accessibility.