This example demonstrates a minimal React application that renders a plain text message, “Hello React!”, to the browser. It uses the React and ReactDOM libraries to create and mount a functional component called `App` into a `div` element with the ID `root`. The page is styled to remove margins and hide overflow, and the production builds of React are loaded from unpkg. No data visualization or external charting libraries are present; it serves purely as a starter template for integrating React into a visualization project.