This D3.js scatter plot visualizes the Iris dataset, mapping petal length and width for each sample. Points are color-coded by species (setosa, virginica, and versicolor) using a custom marker function. The code loads CSV data via `d3.csv`, applies linear scaling with `d3.scaleLinear`, and renders circles as SVG elements. Axis labels are added with rotated text elements, and the visualization uses `d3.axisLeft` and `d3.axisBottom` for axes, with the plot filling the browser window.