A rotating arc or ring of segments indicating work in progress.
Also known as: Throbber, Spinner
A rotating arc says that something is happening but not how long it will take. That is exactly what makes it disliked: it conveys activity without conveying progress.
Indicates that an operation is under way and the interface is not idle, without indicating how much remains.
Contexts: Software
The absence of any indication of remaining time is the recognised weakness of the form, and is why a progress bar is preferred wherever the remaining work can be estimated.
Contexts: Software
An incomplete ring, or a circle of short radiating strokes of graded weight, drawn so that the heaviest part appears to travel around the centre.
Both are used in software contexts.