1.<! DOCTYPE html> declaration helps to display Web pages correctly in the browser
HTML5
<! DOCTYPE html>
HTML 4.01
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en"
"Http://www.w3.org/TR/html4/loose.dtd" >
XHTML 1.0
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en"
"Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >
2.<meta> describing metadata for HTML documents
Define document keywords for search engines:
<meta name= "keywords" content= "HTML, CSS, XML, XHTML, JavaScript" >
Define the Web page description:
<meta name= "description" content= "Free Web tutorials on HTML and CSS" >
Define Page
<meta name= "Author" content= "Hege refsnes" >
Refresh the page every 30 seconds:
<meta http-equiv= "Refresh" content= ">"
<!--optimized for handheld devices, mainly for older browsers that do not recognize viewport, such as BlackBerry--and
<meta name= "handheldfriendly" content= "true" >
<!--Microsoft's Vintage browser--
<meta name= "mobileoptimized" content= ">"
<!--UC Force vertical screen--
<meta name= "Screen-orientation" content= "Portrait" >
<!--QQ Forced vertical screen--
<meta name= "X5-orientation" content= "Portrait" >
<!--UC Mandatory fullscreen--
<meta name= "Full-screen" content= "yes" >
<!--QQ Mandatory fullscreen--
<meta name= "X5-fullscreen" content= "true" >
<!--UC Application Mode--
<meta name= "Browsermode" content= "Application" >
<!--QQ Application Mode--
<meta name= "X5-page-mode" content= "App" >
<!--windows Phone Click No Highlight--
HTML base content (continuous update ...) )