This interactive map displays countries color-coded by income group using a natural Earth projection. A legend to the left allows filtering by income category, dimming non-matching countries while highlighting selected ones. Built with D3 v5, the visualization uses `d3.geoNaturalEarth1`, `d3.geoPath`, and `d3.zoom` for panning and zooming. Country boundaries come from TopoJSON data sourced from the World Atlas, with income values joined from TSV metadata. The color scale uses `d3.scaleOrdinal` with sequential blue schemes.