Differentiate between parameters and filters in Tableau.

A filter restricts which rows reach the view. Its values come from the data, it can be multi-select, and it updates automatically when new members appear.

A parameter supplies a value you define. It does not touch the data by itself — something has to reference it before anything happens. Classic parameters hold one value at a time and are not data-aware.

The distinction matters when you need something a filter cannot do. Swapping the measure on a chart, driving a top-N threshold, or setting a reference line all need a parameter, because a filter can only remove rows.

A common answer to a follow-up: use a filter when you are narrowing data, and a parameter when you are changing what the view *does*.