A line chart visualizes temperature over time for one week in San Francisco, with each day’s timestamp plotted along the x-axis and temperature along the y-axis. React renders SVG elements, while d3.scaleTime, d3.scaleLinear, d3.extent, and d3.line with curveNatural generate the axes and smooth path. Circles mark individual data points, and hover reveals the day via d3.timeFormat. The dataset is loaded as CSV using d3.csv from a GitHub gist.