dfn Question Mark thingy – How to do?

I’ve seen on other people’s sites a great lil’ user-defined hyperlink. When mousing-over, you get a question mark icon, then the definition as alt-type text.

If this is built-in to WP, I’ll be a happy man. I was assuming this is what the “LOOKUP” button did within the admin panel, but best I can tell, it’s just a dictionary link.

If you know of a way to add this balloon help in an easy, admin-panel-non-coder way, I would really appreciate it.

Code example: <dfn title=”This is the text that will appear”>hyperlink text</dfn>

Thanks!
Alan | https://www.bionicgenius.com