Defining Routes in React Router

index.js

import * as React from "react";
import * as ReactDOM from "react-dom";
import { BrowserRouter } from "react-router-dom";
import "./index.css";
import App from "./App";
import * as serviceWorker from "./serviceWorker";

ReactDOM.render(
  <BrowserRouter>
    <App />
  </BrowserRouter>,
  document.getElementById("root")
);

App.js

import * as React from "react";
import { Routes, Route, Link } from "react-router-dom";
import "./App.css";

function App() {
  return (
    <div className="App">
      <h1>Welcome to React Router!</h1>
      <Routes>
        <Route path="/" element={<Home />} />
        <Route path="about" element={<About />} />
      </Routes>
    </div>
  );
}

References
https://reactrouter.com/docs/en/v6/getting-started/installation#create-react-app