A choropleth map colors world countries by economic classification using an ordinal color scale derived from d3.scaleOrdinal and d3.schemeSpectral, with a legend rendered via a custom colourLegend component. Geographic shapes are drawn with d3.geoPath and a Natural Earth projection, while data loads from World Atlas TopoJSON and TSV files. Hovering highlights countries, and d3.zoom enables panning and zooming with animated transitions on the legend circles.