This is not a comparison between popovers and dialogs, nor is it a discussion of support. This is me trying to get ahead of a potential issue for users when developers mix and match the patterns. I will let this 32 second video explain: Sorry, your browser doesn’t support embedded…| Adrian Roselli
HTML| html.spec.whatwg.org
A deep dive into the semantics, behaviours and characteristics of some of the most common user interface elements of websites today.| Hidde's blog
The Popover API provides developers with a standard, consistent, flexible mechanism for displaying popover content on top of other page content. Popover content can be controlled either declaratively using HTML attributes, or via JavaScript.| MDN Web Docs
Open UI| open-ui.org