This visualization shows the hierarchical structure of world countries, organized by continent and subregion, using a tree layout in SVG. The root node is "World," with branches for each continent and further subdivisions down to individual countries. The code uses D3 v5’s `tree`, `hierarchy`, and `linkHorizontal` to compute the layout and draw curved links, with zooming enabled via `d3.zoom`. Text labels are positioned per node, with font size decreasing by depth, and the data is loaded from `data.json` using `d3.json`.