A hierarchical tree visualization displays the world's countries organized by continent and subregion, with each country as a leaf node. The layout uses d3.tree() and d3.hierarchy() to structure the JSON data, while d3.linkHorizontal() generates the curved link paths. Text labels align dynamically based on whether a node has children. Pan and zoom functionality is implemented via d3.zoom(), and margins are applied using the standard D3 margin convention. Custom fonts and text shadows enhance readability.