A collapsible tree diagram displays hierarchical company data in rectangular nodes, with each node color-coded by type (such as product or clinical trial) and collapsible to show or hide child branches. The layout and animation are built with D3 v3’s tree layout and transition methods, while SVG elements render nodes and curved links. Data loads from a JSON file, and the visualization supports zooming and dragging via d3.behavior.zoom, with tooltips appearing on hover.