This example displays a map of world countries as an orthographic projection, rendered in green with blue outlines on a light blue background. It loads geographic data from the world-atlas TopoJSON file using `d3.json` and converts it to GeoJSON with the `feature` function from TopoJSON. The map is drawn as SVG paths using `d3.geoPath` with a `geoOrthographic` projection, creating a spherical globe-like view of the landmasses.