The HTML Specification

The HTML specification uses Document Type Definitions (DTDs) written in the Standard Generalized Markup Language (SGML) to define the details of HTML.

· HTML Transitional: A version of HTML that includes elements to describe font faces and page colors. HTML Transitional represents a version that accounts for formatting elements in older versions of HTML. 

· HTML Strict: A version of HTML that doesn't include any elements that describe formatting. This version is designed to work with CSS driving the page formatting. 

· HTML Frameset: A version of HTML that includes frames, which is markup that allows displaying more than one Web page or resource at a time in the same browser window.

Basic Document Structure

Every HTML page must have the same basic document structure that includes

       a. A statement that identifies the document as an HTML document 
       b. A document header 
       c. A document body