A streamgraph visualizes COVID-19 case counts across Africa, Asia, Europe, America, and Oceania over time. D3 stacked areas with silhouette offset show daily and monthly data, using an ordinal color scale for regions. The code implements tooltips with mouseover events and uses `d3.time.scale` for the x-axis. An alternative view uses `d3.stack` with `stackOffsetSilhouette`, rendering SVG paths with `d3.area` and interactive highlighting to emphasize regional trends.