This choropleth map colors countries by income group using a categorical color scale. A clickable legend filters the map, dimming unselected categories to 10% opacity while highlighting the chosen group. Built with D3 v5, it uses d3.geoPath with a d3.geoNaturalEarth1 projection to render country boundaries from TopoJSON data. The visualization also incorporates d3.zoom for interactive panning and zooming, and animates the legend’s color transitions with d3.transition.