In what ways can PHP sessions be securely managed to differentiate between guest users and registered users in a web application?

To securely manage PHP sessions to differentiate between guest users and registered users in a web application, you can set a session variable upon user login that distinguishes between the two types of users. This session variable can be checked throughout the application to determine the user's status and provide appropriate functionality or content.

// Start session
session_start();

// Check if user is logged in
if(isset($_SESSION['user_id'])){
    // User is logged in (registered user)
    $user_id = $_SESSION['user_id'];
    // Add code here for registered user functionality
} else {
    // User is not logged in (guest user)
    // Add code here for guest user functionality
}