Throbber

A throbber, also sometimes referred to as a loading animation, busy indicator, or activity indicator, is a graphical control element used in a graphical user interface (GUI) to visually indicate that a program is in the process of performing an action in the background. Throbbers serve to reassure the user that the application hasn't frozen or crashed, and that the system is actively working, even if the process takes a noticeable amount of time.

The design and appearance of a throbber can vary widely, ranging from simple animated icons (e.g., a rotating circle, a bouncing ball, or a progress bar) to more elaborate and stylized graphics. The specific animation employed often reflects the overall aesthetic of the software or operating system in which it is used.

While some throbbers provide a visual indication of progress, such as a percentage complete or an estimated time remaining, many are indeterminate, meaning they only signal that a process is underway without giving any specific progress information. This is common when the length or nature of the operation is unknown beforehand.

The primary function of a throbber is to improve the user experience by providing feedback and preventing the user from prematurely terminating or restarting a process that is still running. By confirming that the application is responding, even slowly, the throbber helps manage user expectations and reduces frustration.

Historically, throbbers were more prevalent due to slower processing speeds and network bandwidths. While processing power and internet speeds have significantly improved, throbbers remain a common UI element, especially for tasks that involve substantial data processing, network communication, or complex calculations. The term "throbber" itself is somewhat informal, and its origin is unclear, but it is widely understood within the computing and design communities.