This choropleth map colors countries by income group using an ordinal scale with a spectral color scheme. The visualization supports zooming and panning via d3.zoom, and includes a custom color legend with circles and labels built through reusable D3 selections. Data comes from the world-atlas TopoJSON and TSV files, rendered as SVG paths using d3.geoPath with a natural Earth projection. Hovering highlights countries in red, and tooltips display country names and income categories.