This interactive tree visualization displays world population data organized hierarchically from continent to country to city. Using D3.js v7, it loads a CSV file with columns for Continent, Country, City, and Population, then constructs a hierarchical layout with `d3.tree()` and `d3.hierarchy()`. Nodes are colored by depth level using `d3.scaleOrdinal()`, with circles representing cities and larger nodes for parents. Hovering reveals tooltips showing city population details. The SVG renders vertical links via `d3.linkVertical()` and scales responsively through a viewBox.