What does a venn diagram show?

A Venn diagram is an illustration that uses circles to show the relationship among things or finite groups of things!

A Venn diagram is a visualisation of the probability of events happening of individual events using circles. Probabilities of two events happening at once is shown (this is represented by an intersection) . Probabilities of events not happening is also represented by displaying the probability outside of a circle of an event.

A Venn diagram is a way to related different objects that are interconnected to each other. For example, All boys are intelligent but some boys are handsome. In this scenario, we make a bigger circle that represents intelligent and a circle inside it that will represent boys as all the boys are intelligent. Another circle representing handsome will be outside both the circles but some portion of this circle will be inside the circle with boys as some boys are handsome not all.

Venn diagram is use to show the sets, to find their Union and intersection.

 A Venn diagram shows the logical relation between sets by visualising the elements of the set in a diagram. It uses simple closed curves drawn on a plane to represent sets. 

A Venn diagram is an illustration which is used to display the relationship between different groups of things which generally hold some relationship towards each-other. Anything in the area where circles overlap have a commonality with one another.

it shows element collection overlap area

Venn Diagram shows the rings of the unknown variable to be find and also the intersection among the rings or circles.