A hierarchical tree diagram displays the structure of programming languages, grouped into Web, System, and Data categories. The visualization uses a static dataset defined in JavaScript. D3.js v7 with an SVG rendering approach draws the graph, employing `d3.hierarchy` and `d3.tree` to compute the layout. Nodes are represented as colored circles, color-coded by depth using `d3.scaleOrdinal` with `d3.schemeCategory10`, while links and text labels are appended via D3's data-join methods. The tree is oriented horizontally, placing parent-child connections left-to-right.