What is XHTML?
XHTML is a more formal, stricter version of HTML. XHTML
is defined by an XML dtd which makes it much easier to
* XHTML stands for eXtensible Hyper Text Markup
* It is aimed to replace HTML.
* It is almost identical to HTML 4.01
* It is the reformulation of HTML 4.01 as an application
* It is a stricter, tidier version of HTML.
XHTML 1.0 is the next level of coding as specified by
XHTML is a transition / combination of HTML and XML. To
change from HTML to XHTML requires just a few changes in
your coding styles. The main page to check out is
CONVERTING but all the others provide valuable
information about this coding technique as well.
XHTML provides the framework for future extensions of
HTML and aims to replace HTML in the future. Some
resources refer to XHTML as HTML5.
XHTML 1.0 became an official W3C recommendation on
January 26, 2000. A W3C recommendation means that the
specification is stable, that it has been reviewed by
the W3C membership, and that the specification is now a
XHTML 1.0 is the first step toward a modular and
extensible web environment based on XML (eXtensible
Markup Language). It provides the bridge for web
designers to use a future based coding and still be able
to maintain compatibility with today's browsers.
XHTML is a stricter and cleaner version of HTML.
* XHTML stands for EXtensible HyperText Markup Language
* XHTML is aimed to replace HTML
* XHTML is almost identical to HTML 4.01
* XHTML is a stricter and cleaner version of HTML
* XHTML is HTML defined as an XML application
* XHTML is a W3C Recommendation
XHTML is a combination of HTML and XML (EXtensible
XHTML consists of all the elements in HTML 4.01 combined
with the syntax of XML.
Advantages of using XHTML instead of HTML
1. Documents can be validated much easier
2. Documents can be transformed via tools like XSLT into
other documents for consumption by devices like
3. Fragments of documents can be retrieved faster
4. Text can be stored more effieciently in object
The great thing about XHTML, though, is that it is
almost the same as HTML, although it is much more
important that you create your code correctly. You
cannot make badly formed code to be XHTML compatible.
Unlike with HTML (where simple errors (like missing out
a closing tag) are ignored by the browser), XHTML code
must be exactly how it is specified to be. This is due
to the fact that browsers in handheld devices etc. don't
have the power to show badly formatted pages so XHTML
makes sure that the code is correct so that it can be
used on any type of browser.
XHTML combines XML and HTML 4 to provide developers with
a language that conforms to the XML format, as opposed
to HTML which is based on SGML. XML is much simpler to
parse than SGML, and standards exist such as XSLT, XPath,
and XQuery for manipulating XML documents.
Unfortunately, support for XHTML in browsers is poor,
with the leading browser, Microsoft Internet Explorer,
not supporting the XHTML mime type 'application/xhtml+xml'.
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.
Differences between XML and HTML
Since XML and HTML are derived from SGML they are
similar, but have the following differences:
1. XML is case-sensitive
2. XML must have quotes (single or double) around
3. Most interpreters of HTML are very forgiving about
missing end tags - XML parses are not.
4. Comments start with <-- and end with -->. Inside a
comment, "--" may not appear. Although this is fine in
html, it confuses xml parsers.
How is XHTML better than HTML? Why would you want to use
* to be able to take advantage of new coding techniques
* problems with the earlier versions have been fixed.
XHTML is a fairly close copy of HTML 4.01.
Extensibility : Under HTML, the addition of a new group
of elements requires alteration of the entire DTD. XML
greatly eases the integration of new element collections
as it is a subset of SGML itself and specifies it's own
Portability : By the year 2002 as much as 75% of
Internet access could be carried out on non-PC platforms
such as palm computers, televisions, fridges,
automobiles, telephones, etc. In most cases these
devices will not have the computing power of a desktop
computer, and will not be designed to accommodate
ill-formed HTML as do current browsers.
Currently, the Netscape browser helps greatly for
testing web pages by displaying blank or broken pages
when it comes across sloppy coding. IE is the most
forgiving browser and will show almost any page no
matter the extent of coding errors.
While HTML itself isn't completely lacking in
extensibility or portability but the evolution of it has
been extremely slow compared to the pace of Internet
development. This fuels the problems encountered trying
to make your pages work on a wide range of browsers and
platforms. XHTML will help to remedy those problems.
How To Get Ready For XHTML?
XHTML is not very different from HTML 4.01, so bringing
your code up to the 4.01 standard is a good start. In
addition, you should start NOW to write your HTML code
in lowercase letters.
The Most Important Differences:
* XHTML elements must be properly nested
* XHTML documents must be well-formed
* Tag names must be in lowercase
* All XHTML elements must be closed