The <BASE> URL Tag element provides a base address for interpreting relative URLs when the document is read out of context. The value of the HREF= attribute must be an absolute URL (e.g, "http://www.loc.gov/iug/html/base.html"). The BASE tag is found in the HEAD section of the HTML file. There is no closing tag for <BASE>.
Example:
The BASE tag for this file is
<BASE HREF="http://www.loc.gov/iug/html/base.html">