This visualization displays the hierarchical structure of world countries organized by continent and subregion, using a collapsible tree layout rendered as SVG. The code employs D3 v5’s `tree` layout and `linkHorizontal` generator to draw curved links, with `hierarchy` parsing the nested `data.json` file. Text labels scale in font size based on depth, and a zoom behavior allows panning and scaling via `d3.zoom`. The tree reads from a static JSON dataset and applies Playfair Display typography for readability.