0.4. Is HTML Going Away?
Well, actually, the language has reached middle age in standard Version 4.01 and is not expected to change again. Rather, HTML is being subsumed and modularized as part of Extensible Markup Language (XML). Its new name is XHTML, Extensible Hypertext Markup Language.
The emergence of XHTML is just another chapter in the often tumultuous history of HTML and the World Wide Web, where confusion for authors is the norm, not the exception. At the worst point, the elders of the World Wide Web Consortium (W3C) responsible for accepted and acceptable uses of the language -- i.e., standards -- lost control of the language in the browser "wars" between Netscape Communications and Microsoft. The abortive HTML+ standard never got off the ground, and HTML 3.0 became so bogged down in debate that the W3C simply shelved the entire draft standard. HTML 3.0 never happened, despite what some opportunistic marketers claimed in their literature. Instead, by late 1996, the browser manufacturers convinced the W3C to release HTML standard Version 3.2, which for all intents and purposes simply standardized most of the leading browser's (Netscape's) HTML extensions.
Fortunately for those of us who appreciate and strongly support standards, the W3C took back its primacy role with HTML 4.0, which stands today as HTML Version 4.01, released in December 1999. The standard is clearer and cleaner than any previous ones, establishes solid implementation models for consistency across browsers and platforms, provides strong supports and incentives for the companion Cascading Style Sheets (CSS) standard for HTML-based displays, and makes provisions for alternative (non-visual) user-agents, as well as for more universal language supports.
Cleaner and clearer aside, the W3C realized that HTML could never keep up with the demands of the web community for more ways to distribute, process, and display documents. HTML only offers a limited set of document creation primitives and is hopelessly incapable of handling non-traditional content like chemical formulae, musical notation, or mathematical expressions. Nor can it well support alternative display media, such as handheld computers or intelligent cellular phones, for instance.
To address these demands, the W3C developed the Extensible Markup Language (XML) standard. XML provides the way to create new, standards-based markup languages that don't take an act of the W3C to implement. XML-compliant languages deliver information that can be parsed, processed, displayed, sliced, and diced by the many different communication technologies that have emerged since the Web sparked the digital communication revolution a decade ago. XHTML is HTML reformulated to adhere to the XML standard. It is the foundation language for the future of the Web.
Why not just drop HTML for XHTML? For many reasons. First and foremost, don't expect everyone to just drop everything and start using XHTML standards (Version 1.0 just got recommended in January 2000). There's just too much current investment in HTML-based documentation and expertise for that to happen anytime soon. Besides, XHTML is HTML 4.01 reformulated as an application of XML. Know HTML 4 and you're all ready for the future.
The paradox in all this is that even the HTML 4.01 standard is not the definitive resource. There are many more features of HTML in popular use and supported by the popular browsers than are included in the latest language standard. And there are many parts of the standards that are ignored. We promise you, things can get downright confusing when you're trying to sort it all out.
We've managed to sort things out, so you don't have to sweat over what works with what browser and what doesn't work. This book, therefore, is the definitive guide to HTML and XHTML. We give details for all the elements of the HTML 4.01 and XHTML 1.0 standards, plus the variety of interesting and useful extensions to the language -- some proposed standards -- that the popular browser manufacturers have chosen to include in their products, such as:
And while we tell you about each and every feature of the language, standard or not, we also tell you which browsers or different versions of the same browser implement a particular extension and which don't. That's critical knowledge when you want to create web pages that take advantage of the latest version of Netscape Navigator versus pages that are accessible to the larger number of people using Internet Explorer or even Lynx, a once-popular text-only browser for Unix systems.
In addition, there are a few things that are closely related but not directly part of HTML. For example, we touch, but do not handle, CGI and Java programming. CGI and Java programs work closely with HTML documents and run with or alongside browsers, but are not part of the language itself, so we don't delve into them. Besides, they are comprehensive topics that deserve their own books, such as CGI Programming with Perl, by Scott Guelich, Shishir Gundavaram, and Gunther Birzneiks, and Java in a Nutshell, by David Flanagan, both published by O'Reilly & Associates.
This is your definitive guide to HTML and XHTML as they are and should be used, including every extension we could find. Some extensions aren't documented anywhere, even in the plethora of online guides. But, if we've missed anything, certainly let us know and we'll put it in the next edition.
Copyright © 2002 O'Reilly & Associates. All rights reserved.