The Gantt chart were made by Henry L. Gantt approximately a century ago. Their aim is to provide an immediate comparison between schedule and realty( i.e. among planned work and actual progress of the work). This is attained simply by marking on the chart the planned work and the actual progress of the work.The Gantt chart is in fact a modified bar chart in which horizontal bars are drawn for every activity in proportion to the time required for completing it. A cursor attached to the Gantt chart can be moves across the chart to compare among the actual progress and planned work till any particular date.
There are fundamentally two types of Gantt charts:
1. Order /Activity progress chart2. Machine Load chartIn Gantt chart time in weeks or days is marked together the horizontal axis and the activities or orders are presented along the vertical axis. The amount of work planned or scheduled is marked by the firm lines or blank areas and the actual progress of the work by dotted lines or shaded areas.