A choropleth map colors countries by income group using an ordinal color scale with a spectral scheme. The visualization renders world geography with d3.geoPath and a Natural Earth projection, and supports pan and zoom via d3.zoom. Country names and income groups appear as tooltips, while a custom colorLegend component displays the category labels with colored circles. Data is loaded from TopoJSON and TSV files processed with topojson.feature and d3.tsv.