This example displays a choropleth map of the world, coloring each country according to its economic classification using a spectral color scale. A legend with colored circles and labels explains the mapping. The visualization uses d3.geoPath with a geoNaturalEarth1 projection to render the map from TopoJSON data, and d3.scaleOrdinal with schemeSpectral for the color encoding. Countries highlight in red on hover, and the map supports zooming via d3.zoom.