This is a draft standard for a desktop notifications service, through which applications can generate passive popups (sometimes known as "poptarts") to notify the user in an asynchronous manner of events.
This specification explicitly does not include other types of notification presentation such as modal message boxes, window manager decorations or window list annotations.
Example use cases include:
Presence changes in IM programs: for instance, MSN Messenger on Windows pioneered the use of passive popups to indicate presence changes.
Completed file transfer
New mail notification
Low disk space/battery warnings