Set actions allow you to populate a set with one or more values for one or more dimensions. This is very powerful because sets can be used on any shelf to encode any visual element, can be leveraged in calculations, and can be used as filters. They can be used in all of these ways—and in different ways—in different views. This gives you incredible flexibility in what can be accomplished with set actions. We'll first take a moment to define sets more clearly and then look at an example of a set action.