This visualization displays the hierarchical structure of world countries, organized by continent and subregion, as a horizontal tree diagram rendered in SVG. Using D3 v5's `tree()`, `hierarchy()`, and `linkHorizontal()` APIs, the code reads a JSON data file and positions nodes and connecting paths based on the computed layout. Country names are rendered as text labels with white text shadows, while the paths use a teal stroke. The visualization fills the entire browser viewport, with the page set to fixed positioning and overflow hidden.