This example uses a D3.js tree layout with horizontal links to display a hierarchical dataset of countries organized by continent and subregion. The visualization renders an indented tree where each node’s label is sized relative to its depth, with larger text for higher-level regions. The code employs `d3.hierarchy`, `d3.tree`, and `d3.linkHorizontal` to compute positions and draw the connecting paths, while the `zoom` API enables pan and zoom interactions on the SVG canvas. Styling includes a serif font and green strokes for the link paths.