This choropleth map displays world economies by color, with a legend that filters countries by clicking a color category, dimming non-matching regions. The map uses a natural Earth projection via `d3.geoNaturalEarth1` and `d3.geoPath`, while the legend is built with D3 scales and `d3.schemeSpectral`. Country data comes from the World Atlas TopoJSON and TSV files, rendered as SVG paths with zoom support via `d3.zoom`.