What is a Gannt Chart?

A Gantt chart shows the duration of events over time as horizontal bars, each bar beginning at a start date and extending by a length.

In Tableau it needs a date on Columns, a dimension on Rows, and a measure representing duration on the Size target of the Marks card, with the mark type set to Gantt Bar.

The classic use is project scheduling, but it applies to anything with a start and a duration — order-to-delivery time, machine downtime, how long support tickets stayed open.

Where duration is not stored directly, it is usually a `DATEDIFF` between a start and an end date, created as a calculated field first.