A choropleth map of world countries colored by economic group, with an interactive legend that filters the map to highlight countries matching a selected category. Users click legend items to toggle filtering, which dims all non-matching countries and slightly emphasizes the selected group. The visualization uses d3.geoNaturalEarth1 and d3.geoPath for map projection, d3.scaleOrdinal with d3.schemeSpectral for color encoding, and d3.zoom for pan/zoom. Data comes from the World Atlas TopoJSON and TSV files loaded via d3.tsv and d3.json.