HTML语言的发展史

Question

HTML语言的发展过程

Answer 1

Version history of the standard

Hypertext Markup Language (First Version), published June 1993 as an Internet Engineering Task Force (IETF) working draft (not standard).

HTML 2.0, published November 1995 as IETF RFC 1866, supplemented by RFC 1867 (form-based file upload) that same month, RFC 1942 (tables) in May 1996, RFC 1980 (client-side image maps) in August 1996, and RFC 2070 (internationalization) in January 1997; ultimately all were declared obsolete/historic by RFC 2854 in June 2000.
HTML 3.2, published January 14, 1997 as a W3C Recommendation.
HTML 4.0, published December 18, 1997 as a W3C Recommendation. It offers three "flavors":
Strict, in which deprecated elements are forbidden
Transitional, in which deprecated elements are allowed
Frameset, in which mostly only frame related elements are allowed
HTML 4.01, published December 24, 1999 as a W3C Recommendation. It offers the same three flavors as HTML 4.0.
ISO/IEC 15445:2000 ("ISO HTML", based on HTML 4.01 Strict), published May 15, 2000 as an ISO/IEC international standard.
HTML 4.01 and ISO/IEC 15445:2000 are the most recent and final versions of HTML. HTML's successor, XHTML, is a separate language that began as a reformulation of HTML 4.01 using XML 1.0. It continues to be developed:

XHTML 1.0, published January 26, 2000 as a W3C Recommendation, later revised and republished August 1, 2002. It offers the same three flavors as HTML 4.0 and 4.01, reformulated in XML, with minor restrictions.
XHTML 1.1, published May 31, 2001 as a W3C Recommendation. It is based on XHTML 1.0 Strict, but includes minor changes and is reformulated using modules from Modularization of XHTML, which was published April 10, 2001 as a W3C Recommendation.
XHTML 2.0 is still a W3C Working Draft
There is no official standard HTML 1.0 specification because there were multiple informal HTML standards at the time. However, some people consider the initial edition provided by Tim Berners-Lee to be the definitive HTML 1.0. That version did not include an IMG element type. Work on a successor for HTML, then called "HTML+", began in late 1993, designed originally to be "A superset of HTML…which will allow a gradual rollover from the previous format of HTML". The first formal specification was therefore given the version number 2.0 in order to distinguish it from these unofficial "standards". Work on HTML+ continued, but it never became a standard.

The HTML 3.0 standard was proposed by the newly formed W3C in March 1995, and provided many new capabilities such as support for tables, text flow around figures, and the display of complex math elements. Even though it was designed to be compatible with HTML 2.0, it was too complex at the time to be implemented, and when the draft expired in September 1995, work in this direction was discontinued due to lack of browser support. HTML 3.1 was never officially proposed, and the next standard proposal was HTML 3.2 (code-named "Wilbur"), which dropped the majority of the new features in HTML 3.0 and instead adopted many browser-specific element types and attributes which had been created for the Netscape and Mosaic web browsers. Math support as proposed by HTML 3.0 finally came about years later with a different standard, MathML.

HTML 4.0 likewise adopted many browser-specific element types and attributes, but at the same time began to try to "clean up" the standard by marking some of them as deprecated, and suggesting they not be used.

Minor editorial revisions to the HTML 4.0 specification were published as HTML 4.01.

The most common filename extension for files containing HTML is .html, however, older operating systems, such as DOS, limit file extensions to three letters, so a .htm extension is also used. Although perhaps less common now, the shorter form is still widely supported by current software.

参考资料：http://en.wikipedia.org/wiki/Html#Version_history_of_the_standard