Dialog

A dialog is a supplemental surface that can provide helpful interactions or require someone to take an action before they can continue their task, like confirming a deletion.
Dialogs are often interruptions, so use them for important actions. If you need to give someone an update on an action they just took but that they don't need to act on, try a toast. If you need to give someone additional context that doesn't affect their current workflow, try a popover.