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A bar chart showing duration. Typically used for scheduled and completed work over a period. Invented in 1917 by US engineer-scientific management pioneer, Henry L. Gantt (1861-1919). The chart's horizontal axis maps a timescale. Each activity has its own horizontal rectangle bar projecting time need or used towards the activity's completion. Additional characteristics, such as tart and finish dates, critical and noncritical activities, slack time, and predecessor-successor relationships are helpful displays on a complex, long-duration project. Mainly used in project planning and scheduling. Known also as chronogram.