Sets can either be static or dynamic (changes based on underlying data). Sets are defined using the fields in the Data pane or with marks in the visualization (not dynamic). You can think of sets as groupings or filtered results of your data. One way to create a set is to right-click the field in the Data pane and then select the Create - Set option. In the following screenshot, we will create a set based on values in the Country field:

The Edit Set menu will appear. Select all of the field values for your desired set by clicking the checkbox next to each value. In the following example, all countries with a name starting with the letter A are selected. The name of this set is Countries that start with A. Created sets are shown in the data pane below the measures section:

The next section explains how to give users the ability to edit values used in filters and calculations.