A choropleth map colors countries by economic classification, with an ordinal color scale and a legend showing each category. Built with D3 v5, it uses `geoNaturalEarth1` and `geoPath` for the projection, `topojson` to load world geometry from the world-atlas dataset, and `schemeSpectral` for the color range. The map supports zooming via `d3.zoom`, while hover effects highlight individual countries.