A choropleth map of world economies lets users filter countries by clicking legend items, with unselected countries fading to low opacity. The map uses d3.geoPath with a geoNaturalEarth1 projection and a d3.scaleOrdinal color scale with the schemeSpectral palette, rendering as SVG. The color legend, built with custom enter/merge/exit logic, triggers updates via click handlers that toggle the selected category. Geographic data comes from world-atlas TopoJSON, paired with economic metadata from a TSV file.