A multi-line chart displays a week of temperature readings across multiple cities, with each city represented by a distinct colored line and a color legend. The visualization uses D3 v5’s `scaleTime`, `scaleLinear`, `line` generator with `curveBasis`, and `nest` to group data by city, while `axisBottom` and `axisLeft` render labeled axes. Data is loaded from a CSV file, and the chart is drawn as SVG with a title and a custom color legend.