This example shows a world choropleth map of population data, with each country colored using a sequential square-root scale. Countries with no data appear gray, and hovering reveals a tooltip with the country name and population. The visualization uses D3 v7 with TopoJSON data from world-atlas and CSV population data. It renders SVG paths via d3.geoPath with a geoNaturalEarth1 projection, mapping ISO3 country codes to populations and applying an interpolateYlGnBu color scale.