What is a Measure?

A measure is a field holding quantitative data that can be aggregated — sales, profit, quantity. Tableau shows measures in green.

Placing one on a shelf aggregates it automatically, because each mark can only display a single value. You see this in the pill: `SUM(Sales)` rather than `Sales`. The aggregation is changeable from the field's dropdown — sum, average, median, count, count distinct, minimum, maximum.

The role is assigned by data type on connection and can be changed with Convert to Measure or Convert to Dimension where the guess is wrong.

A useful follow-up to have ready: a field can be used both ways in the same workbook, and you can create a duplicate to have it available as each.