6. THE HISTORY OF HTML and XHTML VERSIONS

6. THE HISTORY OF HTMLand XHTML VERSIONS

Since its initial introduction in late 1991, HTML (and later its XML-based cousin, XHTML)

has undergone many changes. Interestingly, the first versions of HTML used to build the

earliest Web pages lacked a rigorous definition. Fortunately, by 1993 the Internet Engineering

Task Force (IETF) began to standardize the language and later, in 1995, released the first real

HTML standard in the form of HTML 2.0. You will likely encounter more than just the latest

style of markup for many years to come, so Table 1-1 presents a brief summary of the version

history of HTML and XHTML.

HTML or XHTML Version Description

HTML 2.0 Classic HTML dialect supported by browsers such as Mosaic. This

form of HTML supports core HTML elements and features such as

tables and forms, but does not consider any of the browser innovations

of advanced features such as style sheets, scripting, or frames.

HTML 3.0 The proposed replacement for HTML 2.0 that was never widely

adopted, most likely due to the heavy use of browser-specific markup.

HTML 3.2 An HTML finalized by the W3C in early 1997 that standardized most of

the HTML features introduced in browsers such as Netscape 3. This

version of HTML supports many presentation-focused elements such

as font, as well as early support for some scripting features.

HTML 4.0 Transitional The 4.0 transitional form finalized by the W3C in December of 1997

preserves most of the presentational elements of HTML 3.2. It

provides a basis of transition to Cascading Style Sheets (CSS) as

well as a base set of elements and attributes for multiple-language

support, accessibility, and scripting.

HTML 4.0 Strict The strict version of HTML 4.0 removes most of the presentation

elements from the HTML specification, such as font, in favor of using

CSS for page formatting.

4.0 Frameset The frameset specification provides a rigorous syntax for framed

documents that was lacking in previous versions of HTML.

HTML 4.01 Transitional/

Strict/Frameset

A minor update to the 4.0 standard that corrects some of the errors in

the original specification.

HTML5 Addressing the lack of acceptance of the XML reformulation of HTML

by the mass of Web page authors, the emerging HTML5 standard

originally started by the WHATWG3 group and later rolled into a W3C

effort aimed to rekindle the acceptance of traditional HTML and

extend it to address Web application development, multimedia, and

the ambiguities found in browser parsers. Since 2005, features now

part of this HTML specification have begun to appear in Web browsers,

muddying the future of XHTML in Web browsers.

XHTML 1.0 Transitional A reformulation of HTML as an XML application. The transitional

form preserves many of the basic presentation features of HTML 4.0

transitional but applies the strict syntax rules of XML to HTML.

XHTML 1.0 Strict A reformulation of HTML 4.0 Strict using XML. This language is rule

enforcing and leaves all presentation duties to technologies like CSS.

XHTML 1.1 A restructuring of XHTML 1.0 that modularizes the language for easy

extension and reduction. It is not commonly used at the time of this

writing and offers minor gains over strict XHTML 1.0.

3 Web Hypertext Application Technology Working Group (www.whatwg.org).

Beyond the standard forms of markup described in Table 1-1, there are of course various

nonstandard forms in play. For example, the browser vendors introduced various extensions

to HTML and, interestingly, continue to do so. We also have to contend with the ad hoc use

of markup that doesn’t really conform fully to any particular standard other than to what

usually renders in common Web browsers. Such a “tag soup” is certainly not the best way

to approach building Web pages, regardless of whether browsers accept it. Standards for all

forms of markup exist and should be adhered to whenever possible.