This example visualizes a hierarchical tree of world countries organized by continent and subregion, with each country name displayed as a text label. The tree expands horizontally with larger font sizes for higher-level categories, and the entire visualization supports zooming and panning through a zoom behavior. The code builds the layout using `d3.tree` and `d3.hierarchy`, renders links with `d3.linkHorizontal`, and loads data from a JSON file via `d3.json`. Countries are grouped into regions like Southern Asia and Western Asia, with styling applied through SVG paths and text elements.