A React-based scatter chart visualizes hourly Velib bike availability in Paris, aggregated from a remote CSV via `d3.csv` and `d3.rollups`. The SVG rendering uses `d3.scaleTime` for the x-axis (September 6–18, 2021) and `d3.scaleLinear` for the y-axis, with circles sized and positioned by bike counts. D3 generates tick marks, while React components (`AxisBottom`, `AxisTop`, `Marks`) handle layout, and a dropdown filters data options.