This visualization maps social leaders by department over time, plotting each individual as a semi-transparent circle with a tooltip showing their name. The scatterplot uses Vega-Lite’s API with D3.js to fetch CSV data from a REST endpoint, then renders circles sized and colored consistently across a time axis sorted in descending order. The chart relies on Vega-Lite’s mark encoding for positioning and tooltips, while D3 handles data loading and the Vega runtime manages SVG rendering and interactive tooltip behavior.