This visualization displays a choropleth map of world countries colored by income group using a categorical color scale. D3 v6 and topojson load geographic data from the World Atlas, while `geoNaturalEarth1` projection and `geoPath` render the SVG paths. A legend built with `scaleOrdinal` and `schemeSpectral` shows income categories. Pan and zoom interactions are enabled via `d3.zoom`, and hovering highlights countries in red.