Ok, before we continue lets's pick apart our template a little.
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
We defined the doctype of our page as a transitional XHTML 1.0 document with english as the language. The doctype declaration is a required element of any well-formed XHTML page, and references the appropriate DTD (document type definition) for the content of the document.
DTD is used by SGML applications, such as HTML, to specify rules that apply to the markup of documents of a particular type, including a set of element and entity declarations.