This hierarchical tree visualization displays a food-category dataset from a CSV file, organized by root, category, sub-category, and item layers. It uses `d3.stratify()` to build the hierarchy from flat "id,parent" data, then `d3.tree()` to compute the tidy layout. Nodes use distinct shapes and pastel colors per depth, with `d3.symbol()` generating circles, squares, diamonds, and triangles. The code renders links as horizontal paths, provides an interactive tooltip, and includes a legend. The visualization is rendered as an SVG canvas using D3 v7.