This example shows a hierarchical tree of world countries using a horizontal node-link layout. The visualization maps the nested structure of the data to a tree, with text labels sized according to depth level. The code uses D3 v5’s `tree`, `hierarchy`, and `linkHorizontal` to position nodes and draw curved links, while a zoom behavior lets viewers pan and scale the entire SVG. Data is loaded via `d3.json` from a local `data.json` file, with text styled using the Playfair Display font and paths stroked in green.