A choropleth map colors countries according to their economic classification, using an ordinal color scale with a spectral scheme. The map includes zooming and panning via the `zoom` event, and a legend shows the color-to-value mapping. Built with D3 v5, it uses `geoPath` and `geoNaturalEarth1` for the map projection, and the data comes from the `world-atlas` dataset, loaded with `tsv` and `json` calls.