Throbber

A throbber, also known as a loading icon, is an animated graphical control element used to show that a computer 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 indicate how much of the action has been completed.

Usually the throbber is found at the side of a program's toolbar or menu bar. Throbbers take various forms, but are commonly incorporated into the logo of the program. Throbbers are typically a still image (known as its resting frame), unless the program is performing an action, during which time the throbber is animated in a loop to convey to the user that the program is busy (and has not frozen). Once the action is complete, the throbber returns to its resting frame.

It is normally possible for the user to continue interacting with the program while the throbber animated; one such possibility may be to press a "stop" button to cancel the action. Clicking the throbber itself might perform another action, such as opening the program's website, or pausing or canceling the background action.