A progress bar is a component in a graphical user interface used to convey the progress of a task, such as a download or file transfer. Often, the graphic is accompanied by a textual representation of the progress in a percent format.
A more recent development is the indeterminate progress bar, which is used in situations where the extent of the task is unknown or the progress of the task cannot be determined in a way that could be expressed as a percentage. This bar uses motion or some other indicator to show that progress is taking place, rather than using the size of the filled portion to show the total amount of progress, making it more like a throbber than a progress bar.
The concept for the progress bar was invented much earlier. In 1896 Karol Adamiecki developed a chart which he called a harmonogram, which is better known today as a Gantt chart. Adamiecki did not publish his chart until 1931, however, and only then only in Polish. The chart thus now bears the name of Henry Gantt (1861–1919), who designed his chart around the years 1910-1915 and popularized it in the west. The concept was later adopted in computing.