A choropleth map colors world countries according to their economic classification, with a color legend that filters and highlights selected categories. Users can click legend entries to dim non-matching countries and intensify the selected region. Built with D3.js, the visualization uses `d3.geoNaturalEarth1` and `d3.geoPath` to project TopoJSON data from the world-atlas package, while `d3.scaleOrdinal` with `d3.schemeSpectral` assigns colors. Interactive zoom via `d3.zoom` and SVG rendering provide the map interface.