This visualization shows the hierarchical structure of world countries organized by continent and subregion. It renders a horizontal tree layout using D3’s `tree()` and `hierarchy()` functions, with countries positioned as leaf nodes. Links are drawn as curved paths via `linkHorizontal()`, while node labels use varying font sizes based on depth. The entire visualization is placed inside a zoomable group, allowing users to pan and scale through the `d3.zoom()` API. Data comes from a local `data.json` file, and the SVG output is styled with custom CSS, including a serif font and green link strokes.