This example renders a world map using D3.js and TopoJSON. It loads country boundaries from the world-atlas dataset and projects them with `d3.geoMercator`. The map is drawn as SVG paths using `d3.geoPath`, with countries filled in green and outlined in black. The code imports specific functions like `select`, `json`, and `feature` from D3 v5 and TopoJSON, and applies a dark blue background via CSS.