This example presents a basic scatter plot that visualizes the Iris dataset, which users load as a CSV file through a file input. The React application parses the data and, using D3's `select` and `join` API, renders circles within an SVG element. The `viz.js` module configures linear scales via `scaleLinear` and `extent` to map sepal length and width values to the plot's dimensions, styling each point with a fixed radius and fill color. The chart updates whenever a new file is selected.