This example shows the hierarchical structure of world countries, grouped by continent and subregion, as an indented tree of text labels. The visualization uses a D3.js tree layout with hierarchical data, rendered as SVG. It employs `d3.hierarchy` to process the JSON data, `d3.tree` for layout, and `d3.linkHorizontal` to draw the connecting paths. Text labels display country and region names, with font size decreasing by depth, and the view is interactive via `d3.zoom` for panning and scaling.