A line chart displays a week of temperature readings for multiple cities, with each city’s time series drawn as a distinct colored line and a color legend identifying each one. The chart uses D3’s `scaleTime`, `scaleLinear`, and `scaleOrdinal` for scales, `d3.line` with `curveBasis` for path generation, and `d3.nest` to group data by city. The SVG rendering includes axes with gridlines, and data is loaded via `d3.csv`.