Venn There, Done That

A Venn Diagram is a picture that is used to illustrate intersections, unions, and other operations on sets.

The Venn diagrams on two and three sets are illustrated above. The order-two diagram (left) consists of two intersecting circles, producing a total of four regions, , , , and  (the empty set, represented by none of the regions occupied). Here, denotes the intersection of sets  and .