A Venn diagram is a diagrammatic means of representing set relationships. It can be used to show overlapping sets. A Venn diagram consists of two or three sets, called circles, which overlap to form a shape that is known as the intersection. The area inside the shape represents the common members of both sets and hence the overlapping area. The circles are labeled with arbitrary letters (usually A, B and C) and each set is denoted by its corresponding letter in brackets.