This interactive visualization presents the hierarchical structure of world countries, organized by continent and subregion. It uses a horizontal tree layout, with the root node on the left and leaf nodes (countries) extending to the right. The D3.js library (v5) computes the tree layout via `d3.tree`, `d3.hierarchy`, and `d3.linkHorizontal`. Pan and zoom are handled through `d3.zoom`. The data is loaded from `data.json` and rendered as SVG paths and text elements, with node labels sized by depth.