This choropleth map colors world countries by estimated population using a dark red gradient, with a purple hover effect. It loads GeoJSON topology from the World Atlas package and population estimates from an accompanying TSV file, matching them by country ID. The map uses `d3.geoMercator` projection and `d3.geoPath` for rendering, while `d3.scaleLinear` maps population values to colors. Pan and zoom interactions are enabled via `d3.zoom`, and tooltips display country names on click.