A Gantt chart is a popular type of bar chart, showing the interrelationships of how projects, schedules, and other time-related systems progress over time.
In project management, a Gantt chart can show when the project terminal elements start and finish, summary elements (shown) or terminal element dependencies (not shown).
It was developed by Henry L. Gantt by 1910 (see "Work, Wages and Profit" by H. L. Gantt, published by The Engineering Magazine , NY, 1910).
Gantt charts appear in several project management software packages, such as Microsoft Project, Mr. Project or BootChart [1].
See also an excellent discussion of the Gantt chart format on Edward Tufte's website.