Chart Type for Correlation / Distribution. Keywords: correlation, distribution, scatter, relationship, pattern, cluster. Best Chart: Scatter Plot or Bubble Chart. Secondary Options: Heat Map, Matrix. When to Use: Exploring relationship between two continuous variables; identifying clusters or outliers in a dataset. When NOT to Use: Variables are categorical (use grouped bar); fewer than 20 points (patterns aren't meaningful); mobile-primary context. Data Volume Threshold: <500 pts: SVG; 500–5000: Canvas at 0.6–0.8 opacity; >5000: hexbin or aggregate first. Color Guidance: Color axis: gradient (blue → red). Bubble size: relative to 3rd variable. Opacity: 0.6–0.8 to show density. Accessibility: B — Provide data table alternative. Combine color + shape distinction for colorblind users.. A11y Fallback: Data table with correlation coefficient annotation; shape markers (circle/square/triangle) per group. Library: D3.js, Plotly, Recharts. Interactive Level: Hover + Brush.