`<BASE ...>`

Usage Recommendation
use it

HREF: default address for hypertext links

TARGET: default window for linked documents

<BASE ...> tells the browser to pretend that the current page is located at some URL other than where the browser found it. Any relative reference will be calculated from the URL given by <BASE HREF="..."> instead of the actual URL. <BASE ...> goes in the <HEAD> section.

For example, consider a page whose URL is http://www.idocs.com/tags/linking/baseexample.html, and the full code of the page is this:

this code produces this

<HTML> <HEAD> <TITLE>Example of the BASE Tag</TITLE> <BASE HREF="http://www.magenta.com/hello.html"> </HEAD> <BODY> <A HREF="index.html">go home</A> </BODY> </HTML>
this page

The <BASE ...> tag on this page tells the browser to pretend that the page is located at http://www.magenta.com/hello.html. The link on the page makes a relative reference to "index.html". Instead of calculating the full URL of the link as http://www.idocs.com/tags/linking/index.html, the link is calculated as http://www.magenta.com/index.html.

Generally it's best to avoid using <BASE ...>. It usually just restricts the ability to move a set of web pages from one location to another (say, from your computer where you are developing them to the server where they publicly reside). However, <BASE ...> can come in handy in development situations where the final version of the page will make relative references to resources that aren't on the development machine.