This example renders a minimal React application that displays the text message "Hello React!" centered on the page. The code imports React and ReactDOM, defines a functional `App` component returning a single `div` with the class `message`, and mounts it to the DOM element with `id="root"` using `ReactDOM.render`. It demonstrates the basic setup for a React project, relying solely on React's component model and the ReactDOM rendering API. No styling or data manipulation is included beyond the static JSX output.