A Venn diagram is a diagram that shows all possible logical relations between a finite collection of sets. The Venn diagram on the left is an example of union in which two circles overlap. The area that they overlap is the intersection, and the area outside of both circles is the union. The Venn diagram on the right is an example of intersection in which two circles do not overlap. The area where they do not overlap is called the intersection, and the area outside of both circles is called the union. There are 3 types of unions: Intersection, Union, and Complementary. The intersection of two sets is the set of all elements that are members of both sets. The union of two sets is the set of all elements that are members of either set. The complementary union is the set of all elements that are not members of either set.