This choropleth map colors countries by income group, with a hover effect that highlights each nation and a legend displaying the categorical color scale. Built with React, it uses D3 v5 APIs including `geoNaturalEarth1` for projection, `geoPath` for rendering country boundaries, and `scaleOrdinal` with `schemeSpectral` for color mapping. World shape data comes from the world-atlas TopoJSON dataset, and the view supports zooming through `d3.zoom`. The legend is generated by the custom `colorLegend` module.