Blocks of text that are surrounded with <html> and </html> tags are treated as raw HTML; i.e., they are sent to the browser as-is. Since this is a rather dangerous feature, it is disabled by default in the standard install. It is enabled on this wiki for demonstration purposes.

For example, the following:

 <html>
   <span style="color: blue">This is cool!</span>
 </html>

renders as:

This is cool!

In order to enable this feature in your own wiki, see EnablingRawHTML.

There must not be any spaces after the <html> and </html> tags. (As for the <code> and </code> tags.) - MarcTobiasWenzel