Form Action URL Question

Hi,
I'm new to Codeigniter4. And I have a question about something that I don't understand.
First let me say that the tool bar above is difficult to make out even at 120%, the left most icons are difficult to see. But we'll live with it as-is for now.

I created a form that has an action parameter as follows... 

Code:

<form action="<?= base_url() ?>/users/store">

and the resulting action arrives in the correct controller and method, but the URL has a trailing question mark, as follows...

Code:

http://localhost/ci4/users/store? 

 <= where does this question mark come from? 

Ask me questions if needed, I am more than happy to provide more information.
Thanks,
Charles.

What is your form method? Post or get?