Document Structure Elements
Every XHTML document has three major components: the XHTML declaration, the head, and the body. The document structure elements are those that define each component.
Declares the document to be an XHTML document. All document content and supporting XHTML code goes between the <html> and </html> elements.
<html> ... </html>
The <html> element can take the xmlns attribute, which specifies the URL that describes the XML namespace for the document (for example, xmlns="http://www.w3.org/1999/xhtml").
<html> ... all content and XHTML code goes here ... </html>
Although the <html> element is typically the first element in a document, it is ...