This example shows an interactive world map colored by economic classification, using a sequential spectral color scale. Users can pan and zoom the map via d3.zoom, which applies a transform to the geographic group. Hovering highlights individual countries with a red fill via CSS. The visualization loads country boundaries from TopoJSON and metadata from TSV, projecting them with d3.geoNaturalEarth1 and rendering paths with d3.geoPath. It uses d3.scaleOrdinal and d3.schemeSpectral to map economic data to colors, with tooltips showing country names and values.