This example uses D3 v5 to render interactive bar charts from CSV data, displaying multiple series across 26 weekly categories. A custom `makeChart` function builds the visualization with scales (linear and band), axes, and SVG rectangles, while invisible overlay rectangles enable tooltip interactions that show data values for each week. The implementation demonstrates how D3 selections, event handling, and dynamic styling work together to create a coordinated multi-series chart with hover functionality.