This visualization shows the hierarchical organization of world countries, grouped first by continent and then by subregion, using a horizontal tree layout. The code employs D3 v5’s `tree()` and `hierarchy()` functions to compute node positions, then renders the connecting links with `linkHorizontal()` as SVG paths. The data is loaded asynchronously from a local JSON file via `d3.json`. The resulting chart displays countries as leaf nodes without labels, emphasizing the structural branching pattern of the geographic taxonomy.