This choropleth map visualizes global income groups by coloring each country according to its income_grp property. The map uses a natural Earth projection and fills countries with colors from a spectral ordinal scale, with a background legend showing the color categories. Built with D3 v5, the code loads world geometry from TopoJSON and income data from TSV files, then renders the map as SVG paths with zoom support via d3.zoom. The color legend is implemented as a reusable component, and hovering highlights individual countries.