The World Countries Tree visualizes the hierarchical structure of global geography, from continents down to individual countries, using a left-to-right tree layout. It renders an SVG with horizontal link paths, where country names appear as text labels sized by depth. The visualization uses d3.tree() to compute layout positions and d3.linkHorizontal for edge drawing, with d3.zoom enabling pan and zoom interaction. Data comes from the included data.json file, which organizes countries by region and subregion, following a nested JSON structure parsed through d3.hierarchy.