While it is no longer August 4th, John Venn's actual birthday, I just saw Google's 180th birthday shout out and it made venn diagrams 100% more adorable than ever. A little background on Venn: John Venn was a logician and philosopher best known for introducing the Venn diagram. As you can see the circles are used to visually and logically sort groups to show their relationships to each other. A pretty straight forward way to look at different correlations. Thank you John Venn, now can you explain the proper time to use a venn diagram?
You can still check out the full homage to John Venn here.