This interactive D3 tree diagram visualizes a hierarchical dataset of hip replacement services, organizing experts by institution, city, and country. The visualization fetches CSV data from a GitHub gist and uses `d3.csv` to load it, then constructs a nested tree structure through successive filtering and sorting operations. The rendering uses `d3.hierarchy` and `d3.linkHorizontal` to draw the branching layout, with SVG output that responds to the window size. The animation is triggered by node interactions, though the specific transitions are not detailed in the visible code.