Venn diagram. Hope this helps!A Venn Diagram is a graphic organizer that is made up of two or three overlapping circles. In mathematics, Venn diagrams are used to visualize the relationship between two or three sets. Venn diagrams can also be used to compare and contrast the characteristics of any other items, like groups of people, individual people, books, characters, animals, etc. The English mathematician John Venn invented the Venn diagram in 1880.