Overview

A wise programmer once said, "The one constant in computing is change." There couldn't be a truer
statement. This article is about such change, specifically moving from HTML to the next generation, XHTML
(Extensible Hypertext Markup Language).

This article includes the following sections:

An Introduction to XHTML
Implementing XHTML Today
Changing HTML to XHTML
Conclusion
Additional XHTML Resources and Facts
The analysis is from a server-side perspective, meaning it applies equally well to ASP, JSP, PHP or other
server-side driven projects.



An Introduction to XHTML

XHTML (now in version 1.1) is the merging of HTML 4 and XML. It represents such an important advancement
that the World Wide Web Consortium (W3C), the international standards body for the web, is replacing HTML
with XHTML as the standard tool for creating web pages.

XHTML is built to open doors to other formats. For example, XHTML can be used to format content for
pagers, whereas HTML cannot. XHTML will replace WAP and other markup languages. It is a cornerstone in the
revolutionary change in thinking beginning to occur in web site design. Instead of viewing a web site as a
stand alone data island, XHTML will expand web applications, allowing web sites to control and send
information which will drive countless devices, presentation styles and other web sites. XHTML is the
starting point for this tremendous change we are about to experience in how we use the web.

Using XHTML has many advantages over using HTML. Because of its structure, XHTML is faster. Its well
formed documents result in quicker and smaller parsers. These smaller parsers waste less time verifying
and doing logic sorting that's required for hodge podge HTML documents. While faster results are not
available yet, expect improved performance from the next generation of XHTML-based browsers.

The architecture of XHTML allows tags, attributes and document types to be uniquely defined by the users
of XHTML. HTML restrictions no longer apply. Over time, this will allow for the development of industry
and project specific XHTML documents. To explore this idea more fully, see the W3C page.

A significant limitation of HTML today is the form field. The W3C established special task groups to
expand the functionality of XHTML and one of these is working to improve form field usage. The
XHTML/XForms specifications are still under development but when done will dramatically change the way we
use forms. A list of some of the great features XForms will add includes: