A radial tree visualization displays the hierarchy of world countries organized by continent and subregion. Built with D3 v4, it uses the `d3.cluster` layout and custom projection functions to position nodes in a circular arrangement. The visualization supports panning and zooming via `d3.zoom`, with interactive transforms applied to the SVG group. Node labels vary in font size based on depth, and curved paths connect parent-child relationships. The data comes from a local JSON file structured around geographic regions.