This interactive tree visualization presents the hierarchical structure of world countries, organized by continent and subregion, using a horizontal icicle layout where each node is labeled with its geographical name. The visualization uses the D3.js library (version 5.6) with its `tree`, `hierarchy`, and `linkHorizontal` APIs to compute the layout and draw the connecting paths in SVG. The code implements zooming capabilities through D3's `zoom` module, allowing users to explore the hierarchy interactively, while nodes are labeled with varying font sizes based on their depth within the tree. The data comes from a local `data.json` file containing the country classification hierarchy.