This example displays a world map with points representing cities, with circle sizes scaled by population using a square-root scale. It shows a natural Earth projection with graticules and country boundaries overlaid. The visualization uses React to manage state and rendering, while D3 v5 provides `geoNaturalEarth1`, `geoPath`, `geoGraticule`, and `scaleSqrt`. City data comes from a CSV file, and world geography is loaded as TopoJSON. Circles are semi-transparent teal, plotted via projected longitude and latitude coordinates.