Drag circle A (friends who like soccer) and circle B (friends who like basketball) so that they overlap. Press the buttons to highlight each region and see what the overlapping part and the non-overlapping parts actually mean.
The symbols: A∩B (intersection) is what belongs to both, A∪B (union) is what belongs to at least one of them, and A−B (difference) is what is in A but not in B.
💡 Drag circle A completely outside circle B and A∩B becomes empty — sets like this are called disjoint.