A choropleth map colors world countries by economy using an ordinal color scale derived from d3.scaleOrdinal and d3.schemeSpectral. Clicking a legend item filters the map, dimming unselected countries and enlarging the selected one’s stroke. The visualization supports zooming and panning via d3.zoom, uses d3.geoNaturalEarth1 and d3.geoPath for projection, and loads TopoJSON and TSV data from the world-atlas package. A hovering effect turns countries pink.