themes – Load elements without reload page

At the outset, I apologize if this is a trivial question, but I have no idea what exactly I’m looking for.
I have page with categories like this
category list

My goal is when I click on category, page will not reload but will show me elements which are assigned to this category. Each category have one or more elements.
Someone can tell me what am I need. Example will be awesome!

Best Regards,
Bartek