• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

1.4. XHTML: What It Is

You've certainly heard of HTML, but did you know that it is one of many other markup languages? Indeed, HTML is the black sheep in the family of document markup languages. HTML is based on SGML, the Standard Generalized Markup Language. The powers-that-be created SGML with the intent that it be the one and only markup metalanguage from which all other document markup elements would be created. Everything from hieroglyphics to HTML can be defined using SGML, negating any need for any other markup language.

The problem with SGML is that it is so broad and all-encompassing that mere mortals cannot use it. Using SGML effectively requires very expensive and complex tools that are completely beyond the scope of regular people who just want to bang out an HTML document in their spare time. As a result, HTML and other language standards adhere to some, but not all SGML standards,[2] eliminating many of the more esoteric features so that HTML is readily useable and used.

[2] The HTML DTD in Appendix D uses a subset of SGML to define the HTML 4.01 standard.


PREVIEW

                                                                          

Not a subscriber?

Start A Free Trial


  
  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint