Click on a link

Hello.  I am thinking about creating my own website.  I just have a question.  Let's say if there are words that are not very common, and I want my readers to be able to click on the word and then a little window pops up that contains a quick definition for it, how do I do this?

I want to do this so that the reading experience my readers get is smooth.  Thanks.

There are many ways to implement tooltips.  Search for:

HTML tooltip

Here's one way from W3 Schools using HTML and CSS:
https://www.w3schools.com/howto/howto_css_tooltip.asp
 

Thank you.

An easier method might be to just use the title attribute: https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/title