This interactive visualization presents a hierarchical tree of world countries, organized by continent and subregion, with the country names displayed as text at varying font sizes based on their depth. The D3 v5 code uses `d3.tree()` and `d3.hierarchy()` to compute the layout, while `d3.linkHorizontal()` generates curved connecting paths between parent and child nodes. Pan and zoom functionality is implemented through `d3.zoom()`, allowing users to explore the data loaded from a JSON file. The SVG rendering uses a green stroke for the links and a serif font for the labels.