This interactive collapsible tree visualizes a hierarchical dataset about Placemaking Design Learning, with nodes representing categories and subcategories. Users can click any node to expand or collapse its children, with smooth animated transitions. The visualization uses D3 v6’s `d3.tree` layout, `d3.linkHorizontal` for curved links, and SVG elements. It features zoom and pan via `d3.zoom`, and all node and link updates are animated using `transition` with configurable durations.