This example displays a hierarchical tree of technology topics, starting with a root “Technology” node and branching into subcategories like AI, Web, and their children. The data is converted into a hierarchy using `d3.stratify` and laid out with the `d3.tree` function. The SVG rendering uses D3 v7 to draw black links, color-coded circle nodes based on depth, and text labels for each category, all within a React application.