Just as a pedantic aside, people often use Venn diagram when they mean Euler diagram. A Venn diagram always has the overlapping circles and use shading or labeling describe the set relation. Euler diagrams let the circles describe the relation so two non intersecting sets in a Venn diagram might share the left circle green, the right blue and leave the intersection blank or grey. An Euler diagram will have two disjoint circles.

That one made me giggle!