This example demonstrates how to create a world map using D3.js and TopoJSON. It renders country boundaries as green SVG paths with thin black strokes on a dark blue background, using a Mercator projection. The visualization loads geographic data from the world-atlas TopoJSON file and converts it to GeoJSON features with the `feature` function. The code uses `d3.geoMercator` and `d3.geoPath` to project the map coordinates and generate the path data.