npm install react-router-dom
index.js
import { BrowserRouter} from "react-router-dom";
...
<BrowserRouter>
<App />
</BrowserRouter>
App.js
import { Routes, Route, Link } from 'react-router-dom';
...
<div className="App">
<nav>
<Link to="/hello">HELLO</Link> |
<Link to="/test">TEST</Link>
</nav>
<Routes>
<Route path="/hello" element={<Hello/>} />
<Route path="/test" element={<Test/>} />
</Routes>
</div>