Design Principles

Clarity over decoration

The goal of a chart is communication. Every visual element should earn its place by carrying meaning. Anything else is noise that competes for attention and obscures the data.

Minimize chartjunk

Chartjunk is decorative clutter: 3D effects, gradients, heavy gridlines, drop shadows, ornate backgrounds. Edward Tufte's principle of the data-ink ratio says: maximize the ink devoted to data, minimize everything else.

If a decorative element does not encode data, it is competing with the data for the reader's attention. Remove it.

Consistent and honest scales

• Start bar-chart y-axes at zero — truncating exaggerates differences.
• Use consistent scales when comparing multiple charts side by side.
• Label axes clearly with units.

Color with intent

Color is a tool, not decoration. Match the color scheme to the data's type:

• Sequential — ordered data low to high (light → dark blue for temperature).
• Diverging — data with a meaningful midpoint (red ↔ blue for profit/loss).
• Categorical — distinct, unrelated groups (distinct hues for product lines).

Sequential:  light ────────────── dark   (one hue, changing lightness)
Diverging:   color A ──── neutral ──── color B
Categorical: 🔵 🟢 🟠 🟣  (distinct hues, no implied order)

Labeling and accessibility

Directly label series instead of forcing readers to map a legend. Ensure sufficient contrast between colors. Never rely on color alone — about 8% of men are colorblind, so add patterns, labels, or text to distinguish elements.