Monday, May 5, 2008

Introduction to XHTML

The Extensible Hypertext Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax.

While HTML is an application of Standard Generalized Markup Language (SGML), a very flexible markup language, XHTML is an application of XML, a more restrictive subset of SGML. Because they need to be well-formed, true XHTML documents allow for automated processing to be performed using standard XML tools—unlike HTML, which requires a relatively complex, lenient, and generally custom parser. XHTML can be thought of as the intersection of HTML and XML in many respects, since it is a reformulation of HTML in XML. XHTML 1.0 became a World Wide Web Consortium (W3C) Recommendation on January 26, 2000. XHTML 1.1 became a W3C Recommendation on May 31, 2001.

What Is XHTML?

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* 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


Versions of XHTML
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The original XHTML W3C Recommendation, XHTML 1.0, was simply a reformulation of HTML 4.01 in XML. There are three different "DTDs" of XHTML 1.0, each equal in scope to their respective HTML 4.01 versions.

* XHTML 1.0 Strict is the same as HTML 4.01 Strict, but it follows XML syntax rules.
* XHTML 1.0 Transitional is the same as HTML 4.01 Transitional, but it follows XML syntax rules. It supports everything found in XHTML 1.0 Strict, but also permits the use of a number of elements and attributes that are judged presentational, in order to ease the transition from HTML 3.2 and earlier.
* XHTML 1.0 Frameset: is the same as HTML 4.01 Frameset, but it follows XML syntax rules. It allows the definition of an HTML frameset—a common practice early in the timeline of the mainstream Web.

Why the need for XHTML?
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The benefits of migrating to XHTML 1.0 are described above. Some of the benefits of migrating to XHTML in general are:

* Document developers and user agent designers are constantly discovering new ways to express their ideas through new markup. In XML, it is relatively easy to introduce new elements or additional element attributes. The XHTML family is designed to accommodate these extensions through XHTML modules and techniques for developing new XHTML-conforming modules (described in the XHTML Modularization specification). These modules will permit the combination of existing and new feature sets when developing content and when designing new user agents.
* Alternate ways of accessing the Internet are constantly being introduced. The XHTML family is designed with general user agent interoperability in mind. Through a new user agent and document profiling mechanism, servers, proxies, and user agents will be able to perform best effort content transformation. Ultimately, it will be possible to develop XHTML-conforming content that is usable by any XHTML-conforming user agent.

1 Comments:

Blogger LOST DEVIL said...

mast hai jaali

June 29, 2009 at 5:51 AM  

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