This choropleth map colors countries by income group using a red-blue ordinal color scale, with a zoomable Natural Earth projection rendered as SVG paths. It loads world country boundaries from the World Atlas TopoJSON dataset and joins them to TSV metadata by ISO country code. The map includes an interactive color legend built with custom D3 selections, and uses d3.geoPath, d3.geoNaturalEarth1, d3.zoom, and d3.scaleOrdinal with schemeRdBu. Hovering highlights individual countries, and a title tooltip shows each country’s name and income group.