A line chart tracks the cumulative global count of COVID-19 deaths over time, with a prominent horizontal marker line at 10,000 deaths and a vertical “Now” marker at the most recent date. React components use D3’s `scaleTime`, `scaleLinear`, `extent`, and `line` to generate the SVG path, pulling data from a raw GitHub CSV via `d3.csv`. Custom `YMarkerLine` and `XMarkerLine` components draw the reference lines and labels.