Introduction to Html and XHTML

What is HTML

HTML is the lingua franca for publishing hypertext on the World Wide Web. It is a non-proprietary format based upon SGML, and can be created and processed by a wide range of tools, from simple plain text editors - you type it in from scratch - to sophisticated WYSIWYG authoring tools. HTML uses tags such as and to structure text into headings, paragraphs, lists, hypertext links etc. Here is a 10-minute guide for newcomers to HTML. W3C's statement of direction for HTML is given on the HTML Activity Statement. See also the page on our work on the next generation of Web forms, and the section on Web history.

What is XHTML

The Extensible HyperText Markup Language (XHTML™) is a family of current and future document types and modules that reproduce, subset, and extend HTML, reformulated in XML rather than SGML. XHTML Family document types are all XML-based, and ultimately are designed to work in conjunction with XML-based user agents. XHTML is the successor of HTML, and a series of specifications has been developed for XHTML. See also: HTML and XHTML Frequently AnsweredQuestions

Three "flavors" of XHTML 1.0

XHTML 1.0 is specified in three "flavors". You specify which of these variants you are using by inserting a line at the beginning of the document. For example, the HTML for this document starts with a line which says that it is using XHTML 1.0 Strict. Thus, if you want to validate the document, the tool used knows which variant you are using. Each variant has its own DTD - Document Type Definition - which sets out the rules and regulations for using HTML in a succinct and definitive

manner

XHTML 1.0 Strict

Use this when you want really clean structural mark-up, free of any markup associated with layout. Use this together with W3C's Cascading Style Sheet

language (CSS) to get the font, color, and layout effects you want.

XHTML 1.0 Transitional

Many people writing Web pages for the general public to access might want to use this flavor of XHTML 1.0. The idea is to take advantage of XHTML features including style sheets but nonetheless to make small adjustments to your markup for the benefit of those viewing your pages with older browsers which can't understand style sheets. These include using the body element with bgcolor, text

and link attributes.

XHTML 1.0 Frameset

Use this when you want to use Frames to partition the browser window into two or

more frames

المصدر:http://www.w3.org/MarkUp/.