When to use
Use a progress bar to communicate to the user that a process requires load time. The exact amount of progress could either be known or unknown. When progress is unknown, use an indeterminate progress bar (instead of determinate).
When space is little, consider using a progress spinner. This is a circular variant of a progress indicator that also supports indeterminate and determinate operations.
Behaviour
A progress bar communicates progress by animating the indicator along the length of the track. Specific behaviour depends on the type of operation (indeterminate or determinate).
Placement
Several placement options depend on the context. Examples are:
- Placement at the center of the screen can indicate loading all screen content.
- Attached to a container can indicate the process applies to that particular item or a spot where additional content will be loaded.