A line chart displays one week of temperature data for multiple cities, with each city represented by a colored line. The visualization uses D3 v5's `scaleTime`, `scaleLinear`, and `scaleOrdinal` to map time and temperature, while `nest()` groups the data by city and `line()` with `curveBasis` smooths each series. Color-coded lines are sorted by their final temperature values, and a custom `colorLegend` function renders a categorical legend. The data originates from Data Canvas - Sense Your City, showing temperatures in Celsius.