This interactive collapsible tree visualization displays hierarchical data from the flare-2.json dataset. Users can click on nodes with children to expand or collapse branches, with smooth animations transitioning nodes and links to their new positions. The visualization uses D3.js v6, specifically leveraging `d3.hierarchy`, `d3.tree`, `d3.linkHorizontal`, and the `transition` API to animate the layout changes. Animated zooming and panning through `d3.zoom` enhances navigation of the complex hierarchical structure.