<meta http-equiv = "Content-type" content="text/html;charset=utf-8" />

上面这种方式是HTML4中设置页面字符集的标签

5秒一刷新

<meta http-equiv="refresh" content="5"/>

5秒以后跳转到百度

<meta http-equiv="refresh" content="5,url=http://www.baidu.com" />

网页关键词

<meta name="keywords" content="网站关键词1,2,3,4" />