This choropleth map visualizes global population estimates, with each country filled in a dark red gradient according to its population. The visualization uses the `topojson` library to extract country features from a GeoJSON file and renders them with `d3.geoPath` and a Mercator projection. Population data is loaded from a TSV file, and color is assigned via `d3.scaleLinear`. A zoom interaction, implemented with `d3.zoom`, adjusts the paths’ transform on zoom events.