Design
Contrast Ratio
Plain-language definitionA numerical comparison between the luminance of foreground and background colors. Sufficient contrast supports readable text and distinguishable controls.
Why it matters
Use the term to make a better decision.
In practice, contrast ratio matters when a team needs to connect a technical or creative choice to a visible change in clarity, performance, discovery, or conversion. The useful question is not whether the term sounds sophisticated. It is what decision it helps the team make.