This choropleth map uses a Yellow-Orange-Red sequential color scale to show population density values for a subset of countries, with denser regions appearing darker. It plots country shapes from the world-atlas TopoJSON file onto an SVG canvas using the D3.js `geoNaturalEarth1` projection and `geoPath()` generator. Population figures are loaded from a CSV file and stored in a JavaScript `Map` for lookup by country name, with missing or unknown countries rendered in a neutral gray. Hovering over a country triggers a tooltip that displays the country’s name and density value, and a legend with color swatches below the map communicates the scale.