This visualization displays course demand statistics as multi-line time series, with each line representing a different course ID and tracking count values over dates. The chart uses D3 v5 with SVG rendering, employing `d3.nest()` to group data by course ID, `d3.line()` with `curveBasis` for smooth paths, and `scaleTime`/`scaleLinear` axes. A color legend appears on the right, generated by a custom `colorLegend` module, while the data is filtered to show only the first three courses from a CSV source.