What are the best practices for implementing authentication in React.js applications?

For implementing authentication in React.js applications, consider using JSON Web Tokens (JWT) for stateless authentication. You can use libraries like `react-router-dom` to create protected routes accessible only to authenticated users and store the authentication state in a global context or a state management library like Redux. As for precautions, make sure to securely store tokens, preferably in HTTP-only cookies to prevent XSS attacks. You should also remember to implement an authentication service on your backend to issue and validate tokens. Lastly, ensure proper session management and add security measures like CSRF protection.