A choropleth map of world countries, colored by ordinal income group, includes a color legend that filters the map when clicked. Clicking a legend label dims all countries except those in that group; clicking the same label again clears the filter. The map uses the `geoNaturalEarth1` projection with SVG paths generated by `geoPath`, and the legend re-renders via an `onClick` handler. Data is loaded from a world-atlas TopoJSON and TSV files.