How can sessions and cookies be effectively utilized in PHP to store and manage data between multiple page loads for improved performance and user experience?

Sessions and cookies can be effectively utilized in PHP to store and manage data between multiple page loads by storing user-specific information such as login credentials, shopping cart items, or user preferences. Sessions are stored on the server and are accessible across multiple pages during a user's visit, while cookies are stored on the user's browser and can persist even after the user leaves the site. By using sessions and cookies, you can improve performance and user experience by maintaining user data without the need to constantly retrieve it from a database.

// Start a session
session_start();

// Store data in session
$_SESSION['username'] = 'JohnDoe';

// Set a cookie
setcookie('user_id', '123', time() + 3600, '/');

// Retrieve data from session
$username = $_SESSION['username'];

// Retrieve data from cookie
$user_id = $_COOKIE['user_id'];