A choropleth map colors countries by their economy category, using an ordinal color scale with a spectral scheme and a custom legend that displays each category as a colored circle with a label. The map renders geographic shapes via `d3.geoPath` with a natural Earth projection, while `topojson.feature` converts TopoJSON world-atlas data into GeoJSON features. Users can pan and zoom the map through `d3.zoom`, and hovering over a country highlights it and reveals its name and economy type in a tooltip.