A choropleth map colors countries by their economic classification using an ordinal color scale with a spectral scheme. The visualization loads world geometry from TopoJSON and country metadata from TSV, joining them by ISO numeric codes, and renders with D3’s `geoNaturalEarth1` projection and `geoPath`. A custom `colorLegend` displays the scale, while zooming and panning are enabled via `d3.zoom`. Hovering highlights countries, and tooltips reveal name and economy class.