A scatter plot of the Iris dataset displays sepal width against petal length, with points colored by species. An interactive color legend on the right filters the visualization: hovering over a species name highlights matching points while dimming all others to 20% opacity. Built with React and D3 v5, the example uses `scaleLinear` and `scaleOrdinal`, SVG circles, and `onMouseEnter`/`onMouseOut` events to drive the hover state. The data loads via `d3.csv` from a gist.