A line chart displays website visitors by source, with visitor counts plotted along the y-axis and source categories along the x-axis. The visualization uses d3.v7's `d3.csv` to load data from a remote gist URL, `d3.scaleLinear` for both axes, and `d3.line` to generate the steelblue path. Axis labels are rendered with `d3.axisBottom` and `d3.axisLeft`, and source labels are rotated 40 degrees. The chart title and axis titles are added as SVG text elements.