What are the best practices for handling user logins and logouts in a PHP system to avoid conflicts between multiple users?

To avoid conflicts between multiple users during login and logout processes in a PHP system, it is important to properly manage user sessions. This can be achieved by using session variables to store user information securely and ensuring that sessions are properly destroyed upon logout. Additionally, implementing proper error handling and validation mechanisms can help prevent unauthorized access to user accounts.

// Start session
session_start();

// User login process
if(isset($_POST['login'])) {
    // Validate user credentials
    // If valid, set session variables
    $_SESSION['user_id'] = $user_id;
    $_SESSION['username'] = $username;
}

// User logout process
if(isset($_GET['logout'])) {
    // Destroy session variables
    session_unset();
    session_destroy();
}