This visualization uses a natural Earth projection map to display the population of each country for 2018, with the area of each circle proportional to its population. The map supports pan, zoom, and hover interactions for additional details. The code employs d3.geoPath and d3.geoNaturalEarth1 for the map projection, along with d3.scaleSqrt for sizing the circles. Population data comes from a CSV file, while country boundaries are sourced from TopoJSON. Legends for both color and size are rendered using SVG, with hover effects revealing population figures.