This example visualizes population by country using circles overlaid on a world map, with the area of each circle proportional to the country's 2018 population. The map uses a natural Earth projection, and users can pan and zoom the view. Hovering over a country reveals a tooltip with the country name and population. A size legend and color legend help interpret the circles, and countries with missing data appear in a distinct color. The visualization uses D3 v5 and renders in SVG, with zoom and hover interactions for exploration.