The HTML <base> element specifies the base URL to use for all relative URLs in a document. There can be only one <base> element in a document.

Full information at https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base

Routing or URL rewriting with base tag

Let's say you are located at:

www.domain.com/folder/subfolder/

Now if in your index.html file, you have the anchor tag to redirect to test.html as -

<a href="test.html">Click here</a>

Then this anchor will be regular anchor and will leads to

www.domain.com/folder/subfolder/test.html

Now if you will add base tag in your index.html's head tag as -

<base href="http://www.domain.com/" />

Then your same anchor

<a href="test.html">Click here</a>

now will lead to

www.domain.com/test.html

With all that being said, I highly recommend you keep learning!

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