The term "modal" pre-dates <dialog> by a huge amount, and generally refers to a popup within the same window that prevents interacting with what's behind the po

The term "modal" pre-dates <dialog> by a huge amount, and generally refers to a popup within the same window that prevents interacting with what's behind the popup (I believe the term comes from how you "change modes" when it appears). On the web they used to be implemented using <div> and CSS, often with some sort of javascript library so you didn't have to do it yourself.