This example shows a world map rendered as gray countries with white borders, overlaid with white circles marking populated places from Natural Earth data. Hovering over a country or city highlights it in pink or blue, respectively. The visualization uses D3 v3's `d3.geoMercator` projection and `d3.geoPath` to draw GeoJSON features from two remote sources: world-110m.geojson for countries and ne_50m_populated_places_simple.geojson for places. Circles are positioned via the projection’s coordinates and respond to mouseover and mouseout events.