The circles in a Venn diagram represent groups of things with a shared attribute. The circle overlap areas represent those aspects belong equally to both groups. For example, the Venn diagram here describes the relationship between the political and geographical entities related to Britain, UK, British Isles, etc
Circles in a Venn diagram can overlap partially, overlap completely, or even be totally separate — letting the viewer see the relationship between the groups at a glance.
Venn diagrams have many uses:
- Explaining systems of taxonomy
- Displaying organizational systems
- Exploring different classes of items
- Winning internet arguments
You can easily make a Venn diagram using ClassTolls.net or Gliffy or Bioinformatics & Evolutionary Genomics