This choropleth map uses a Natural Earth projection to visualize population data for 20 countries, with darker blue shades representing higher values. The visualization loads world geometries from the world-atlas TopoJSON dataset via `d3.json` and merges CSV population data using a lookup dictionary. Countries are rendered as SVG paths using `d3.geoPath`, with missing data shown in light gray. A sequential blue color scale (`d3.scaleSequential`) and gradient legend communicate the population range, while a tooltip displays exact values on hover.