This example shows a force-directed node-link diagram depicting relationships between four services, with nodes colored by a categorical scale and a tooltip revealing each node's ID on hover. The visualization uses d3.forceSimulation with `d3.forceManyBody`, `d3.forceLink`, and `d3.forceCenter` to compute the layout, rendering nodes as circles and links as lines updated on each tick. Data is loaded from a CSV with d3.csv, and the SVG drawing includes animated transitions for node resizing and tooltip opacity via the d3 transition API.