The World Countries Tree visualizes a hierarchical dataset of countries organized by continent and subregion as a labeled, zoomable tree diagram. It uses D3's `tree` layout and `linkHorizontal` path generator to draw curved links between nodes, rendering text labels whose font size decreases with depth. Implemented with D3 v5, the chart supports interactive pan and zoom through `d3.zoom`, with an SVG container and data loaded from a static JSON file.