This example shows a multi-series line chart comparing math, reading, and writing scores across sampled students, with interactive hover tooltips displaying exact values for each score type. The visualization uses D3 v7 to load CSV data from a GitHub gist, downsamples every 10th record, and renders the series with `d3.line` and `d3.curveMonotoneX` on an SVG canvas. Horizontal gridlines, a legend, and axes are generated via `d3.axisLeft` and `d3.axisBottom`. Three colored lines—steelblue, tomato, and seagreen—represent the respective subjects, with hover circles attached via `mouseover` events to populate the tooltip div.