This interactive chloropleth map displays world countries colored by income group, with a legend showing the categorical color scale. The visualization uses d3.geoNaturalEarth1 projection and d3.geoPath to render geographic boundaries from TopoJSON world data loaded via topojson.feature, while country names and income values come from a TSV file merged by ISO code. Users can pan and zoom using d3.zoom, and hovering highlights countries in red via CSS. The ordinal color scale employs d3.scaleOrdinal with the d3.schemeSpectral palette, and a custom colorLegend component renders circles and text labels.