An HTML user agent should use the SGML declaration that is given in section SGML Declaration for HTML . Some of the elements are delimited explicitly by tags, while the boundaries of others are inferred. The HTML element contains a HEAD element and a BODY element . HTML Lexical Syntax SGML specifies an abstract syntax and a reference concrete syntax. This section is only a summary.
Some markup also maps to data character strings.
Numeric character references map to single- character strings, via the document character set . Each reference to one of the general entities defined in the HTML DTD maps to a single- character string. Tags Tags delimit elements such as headings, paragraphs, lists, character highlighting, and links. Most HTML elements are identified in a document as a start-tag , which gives the element name and attributes, followed by the content, followed by the end tag . The content of an element is a sequence of data character strings and nested elements.