This line chart displays the cumulative global death toll from COVID-19 over time. A horizontal marker line at 1,000,000 deaths and a vertical marker at the most recent date highlight key thresholds. The chart uses D3’s `scaleTime`, `scaleLinear`, and `line` to generate the SVG path from the CSSE COVID-19 time-series data, while React renders the visual and the custom `YMarkerLine` and `XMarkerLine` components draw the annotations.