A hierarchical treemap visualizes stock expiration data, grouping products by brand, category, and lot, with rectangle size reflecting quantity. The view is interactive, allowing users to click parent nodes to drill down into subcategories. Built with D3.js v4, it uses `d3.treemap`, `d3.hierarchy`, and `d3.nest` to structure the data. Color scales encode alert levels and expiration urgency. SVG rendering with hover tooltips displays details. The hierarchy is derived from a CSV with dimensions like item name and expiration days.