The visual cue, typically an animated icon, signifies that the application is in the process of retrieving or processing data. It informs the user that the application has received a request and is working to fulfill it, preventing the impression that the system is unresponsive. A rotating circle or a series of animated dots are common examples.
This indicator is vital for user experience, reducing frustration during periods of latency or data transmission. Its presence assures the user that the application is functioning correctly, even if content is not immediately visible. Historically, the absence of such indicators often led users to prematurely close the application or repeatedly attempt the same action, potentially exacerbating server load.