This example displays a hierarchical tree of world countries organized by continent and subregion, rendered as an SVG visualization. The data is loaded from a JSON file using `d3.json()`, then processed through `d3.hierarchy()` and `d3.tree()` to compute the layout. Nodes are labeled with country names, with font size scaling by depth, and links are drawn using `d3.linkHorizontal()`. Pan and zoom interactions are implemented with `d3.zoom()`, while hover effects are omitted.