This choropleth map visualizes countries color-coded by income group, using a yellow-green sequential color scale. The map renders world countries as SVG paths via `d3.geoPath` with a `geoNaturalEarth1` projection, and includes an interactive color legend built with a custom `colorLegend` component. Hovering highlights countries in red, while tooltips show the country name and income group. The visualization loads and joins geographic and tabular data from the `world-atlas` package using `Promise.all` with `d3.json` and `d3.tsv`, then processes it with `topojson.feature`.