A choropleth world map visualizes population data for select countries, using a red sequential color scale to encode values and a legend for reference. Built with D3 v7 and TopoJSON, it uses `d3.geoPath` and `d3.geoNaturalEarth1` for projections, loading country boundaries from a world-atlas package and population values from a Gist JSON file. Hovering over a country reveals a tooltip with its population in millions.