This interactive choropleth maps world population by country, with a dropdown to switch between years (1980–2030) and a sidebar ranking the top ten most populous nations. It uses D3 v6 with `d3.geoPath`, `d3.geoMercator`, and a `d3.scaleThreshold` color scale, pulling CSV data from a GitHub repository and GeoJSON country boundaries. Hovering reveals a tooltip with the country name and population, while the map redraws on year selection.