This interactive choropleth map visualizes global population density (people per km²) across countries for the years 1980, 2000, 2010, and 2022. A dropdown menu switches between years, updating the color-coded SVG paths rendered with d3.geoPath and a Mercator projection. A sidebar displays the ten most densely populated countries, while hovering over a country reveals its name and density value via a styled tooltip. Data is loaded as CSV files and the world geometry from a GeoJSON source.