A hierarchical tree map displays the geographic organization of world countries, branching from continents into subregions and individual nations. The visualization reads country names from a nested JSON file, structured by continent and subregion. Implemented with D3 v5, the tree layout computes node positions while horizontal links connect parent and child nodes via the `linkHorizontal` path generator. Zoom functionality is enabled through `d3.zoom`, and each country label’s font size scales inversely with depth, making higher-level categories larger and more prominent.