This example presents a tree graph of internet speed data, organizing countries by classification (High, Medium, or Low) and displaying each country’s aggregated broadband and mobile speeds as leaf nodes. The visualization uses D3 v7 APIs including `d3.tree`, `d3.hierarchy`, and `d3.linkHorizontal` to render the hierarchical structure in SVG. Data is loaded from a remote CSV file and preprocessed into a nested tree format, with nodes colored by classification. The code also includes a force-directed network graph using `d3.forceSimulation` and `d3.forceLink`, though only the tree is shown in the SVG.