This visualization displays the hierarchical structure of world countries, organized by continent and subregion. The data is presented as a horizontal tree layout with curved link paths connecting parent nodes to their children. Built with D3 v5, the code uses `d3.tree` and `d3.hierarchy` to compute the layout, `d3.linkHorizontal` for the paths, and `d3.zoom` for panning and scaling. Country names are rendered as text labels with sizes that decrease at deeper hierarchy levels.