This example visualizes global population data by overlaying semi-transparent circles on a natural Earth projection map. The circles are sized using `d3.scaleSqrt` based on 2018 population figures, and hovering over countries reveals their population via a tooltip. The visualization uses `d3.geoPath` with `geoNaturalEarth1` for map projection, `d3.zoom` for panning and zooming, and includes both a color legend and a size legend built from `d3.scaleOrdinal` and `d3.scaleSqrt`. Data is loaded from a CSV file and TopoJSON world atlas using `d3.csv` and `d3.json`.