This interactive world map visualizes population density by country for the years 1980, 2000, 2010, and 2022. Users select a year from a dropdown menu to update the choropleth map, where darker colors indicate higher densities. The visualization uses d3.geoPath, d3.geoMercator, and d3.scaleThreshold to render geographic data from a TopoJSON file and CSV data loaded from GitHub. Hovering over a country reveals a tooltip with its density, and a ranking table displays the top ten most densely populated countries.