A throbber is a graphic found in a graphical user interface of a computer program that animates to show the user that the program is performing an action in the background (such as downloading content, conducting intensive calculations or communicating with an external device). In contrast to a progress bar, a throbber does not convey how much of the action has been completed.

Throbber
Multi-stage throbber
Multi-stage throbber
COP & THROBBER; Ex-Policeman Holds Lust-Crazed Pounds 80-a-Head Orgies at Mansion
Cops and throbbers
Icon? I Can
Ajax for Java developers: Build dynamic Java applications
Graphical user interface builder
One Hundred Million Years of Solitude
Dear Heart