This visualization displays the hierarchical structure of world countries, organized by continent and subregion. It uses a horizontal tree layout, with each country name rendered as a leaf node and connections drawn as curved links. The code employs D3 v5’s `tree()` layout, `hierarchy()`, and `linkHorizontal()` path generator to position nodes and draw edges in SVG. Data comes from a local `data.json` file containing the nested geographic grouping.