Venn diagram in 1880: Encoding

John Venn, 1880; Euler drew related region diagrams earlier intersection area of overlapping closed curves Yes if one claim is visible at a glance in Meta, Google and retail print; otherwise link to a full figure. Yes for lab reports and poster boards if axes, units and a source line are present.

Excel or Google Sheets or PowerPoint; export SVG/PDF. Do not rely on hue alone. Label directly and check greyscale. Venn diagram: honour intersection area of overlapping closed curves, and switch when four-plus sets, or when sizes must be to scale. The core mark of Venn diagram is intersection area of overlapping closed curves.

two or three sets with a real overlap story The eye compares length and position more accurately than area. PowerPoint, Excel or Google Sheets and Meta, Google and retail print share the same geometry. Decoration rarely persuades; it slows reading. Perspective distortion wrecks comparison. Keep it flat.