The Venn diagram - in general - is readable as that circles that overlap depict sets of items that share traits of the commonalities, while circles that do not overlap show items that have no common traits.

Basically, showing the similarities and differences between two concepts is their main purpose, and so Venn diagrams are appreciated as an educational tool. Since the mid-20th century, they have been used at the elementary school level to introducing logic.

Venn diagram history

Even though the origin of Venn diagrams goes back much further, they are named after British logician John Venn, who wrote about them in an 1880 paper entitled “On the Diagrammatic and Mechanical Representation of Propositions and Reasonings” in the Philosophical Magazine and Journal of Science.