Authentication with React Router v6: A complete guide

React Router is a widely-used library in React applications that provides a component-based approach to handle routing, URL parameters, redirects, and data loading, with its version 6 introducing new concepts like `<Outlet />` and layout routes. The article outlines a comprehensive tutorial on setting up React Router in a React application, focusing on creating protected routes, implementing user authentication, and integrating two-factor authentication (2FA) to enhance security. It details the use of custom hooks like `useAuth` and `useLocalStorage` to manage user authentication state and demonstrates how to create protected routes using the `ProtectedRoute` component. Additionally, the tutorial explores nested routes, the use of `<Outlet />` for rendering child components, and the introduction of data APIs in React Router v6.4 to manage data fetching and state handling within a React application. The article also covers advanced topics such as passing state and functions through React Router, offering solutions to challenges posed by React Router's limitations on handling non-serializable state.