A scatter plot visualizes the Iris dataset, mapping sepal length to the x-axis and petal length to the y-axis, with each species represented by a distinct symbol. The example uses the D3.js library, specifically its `scaleLinear` for axes, `scaleOrdinal` for the shape scale, and `symbol` to generate the marks. A custom shape legend, built via a separate module, identifies the species. The data is loaded asynchronously from a CSV file hosted on GitHub, and the visualization fills the browser window.