This example demonstrates a reusable scatter plot visualizing the Iris dataset, plotting petal length against sepal length. D3.js v7 fetches the CSV data asynchronously, and the code uses d3.scaleLinear, d3.extent, d3.axisLeft, and d3.axisBottom to map values to SVG circles. The rendering uses a full-window SVG canvas with fixed margins, and the scatter plot marks are drawn via chained d3.select and `.join('circle')` operations.