I was working on a web page generation program recently and was looking for a way to present different versions of the same page with slight differences in the markup and styles. Although using the iframe element came to mind I wasn't keen on rendering out lots of different versions of the page and then referencing them individually in each iframe.
In order to validate any page of HTML or XHTML you will need a doctype. This is a string of text that sits at the top of the document and tells the browser exactly what markup standard has been used to create the page.
To get a webpage to refresh every few seconds you can use a meta tag with the attribute http-equiv and a value of refresh. The number of seconds to delay can be put into the content attribute. This meta tag (as will all meta tags) goes into the head section of the document.
Here is an example that refreshes the page every 2 seconds.
Adding a hyper link for an RSS or Atom feed on your web page works, but that's not all you can do. By adding a link to the head section of the page you can allow your users an alternative method of picking up your feed.
To add an RSS feed use this.