This example presents an interactive world map using a geographic projection. It displays countries as colored regions with a blue sphere background, and hovering over a country changes its fill to red. The visualization is built with D3 v5 and TopoJSON, using `d3.geoEquirectangular` for the projection and `d3.geoPath` to render the map. Country boundaries and shapes come from the world-atlas dataset (countries-110m.json), with SVG paths styled via CSS classes.