This choropleth displays world population figures for a selection of countries, with darker blues representing higher populations and gray for countries without data. It uses a Mercator projection via `d3.geoMercator` and `d3.geoPath` to render country boundaries from a TopoJSON world-atlas dataset. Population values are mapped through a sequential `d3.scaleSequential` with an `interpolateBlues` color scale. Hovering reveals a tooltip with the country name and population in millions, powered by SVG `title` elements.