This map visualization displays global population estimates for 2018 using circles overlaid on a geographic projection. Semi-transparent cyan circles, sized by population magnitude, are placed at country centroids using `d3.geoCentroid` and rendered with `d3.geoNaturalEarth1` and `d3.geoPath`. A size legend with `d3.scaleSqrt` and a color legend explain the mapping. Data comes from a UN population CSV merged with TopoJSON world boundaries; zooming is enabled via `d3.zoom`, and hover reveals population details.