This interactive choropleth map displays world countries colored by their economic classification, with grayed-out, semi-transparent countries when one is selected. Clicking a country highlights it and shows its name and value in a tooltip; clicking again deselects it, and clicking a color legend swatch filters the map to that category. Built with D3 v5, it uses `d3.geoNaturalEarth1` for projection, `d3.geoPath` for rendering SVG paths, and `topojson.feature` to convert TopoJSON from the world-atlas package, joined with TSV metadata containing ISO codes and economy data.