Encode the important comparison as position or length on a shared axis

Readers compare positions along a common scale, such as the ends of bars or points on a line, more easily than angles, areas or color shades. Put the comparison that carries your message on that channel.

• To compare categories, use bar length or dot position on one axis.
• To show change, use position over time on a line.
• Use color to group or highlight, not to carry the main quantity, unless the chart is a map or heatmap where position is already used.
• Avoid encoding quantities as bubble area when readers need to compare them closely.

Sort bars by value unless the categories have a natural order, such as age bands or months.