A vertical tree diagram displays three levels of food categories, from the root "Food" down to fruits, vegetables, dairy, and their individual items. The SVG visualization uses D3 v7's `d3.stratify` and `d3.tree` layouts, reading hierarchical data from a local `food_tree.json` file. Node circles are colored by depth using a `d3.scaleOrdinal` with blue, orange, and green, while `d3.linkVertical` draws the connecting paths between parent and child nodes.