Banner
A prominent, inline message that communicates a contextual status — a success, a warning, an error, or a piece of information — directly within the page flow.
Dialog
A modal overlay for focused tasks and decisions — confirmations, short forms, or anything that should interrupt the page until the user responds. It dims the surrounding UI, takes focus, and dismisses on backdrop press or the built-in close affordance.
Spinner
An indeterminate loading indicator — a small spinning ring you show while content, a request, or an action is still in flight and you can't yet report progress as a percentage.