This example presents a hierarchical tree of world countries, organized by continent and region, using a horizontal layout with curved links. It visualizes geographic groupings from a local `data.json` file, with depth-based font sizing for region names versus country names. The implementation leverages D3 v5’s `tree()` layout, `hierarchy()`, and `linkHorizontal()` path generator, rendering as SVG. Pan and zoom interactions are enabled via `d3.zoom()`, while text styling uses CSS text-shadow for legibility.