This code checks whether the session is active or not and displays a corresponding message. Package Library: PHP 5 >= 5.4.0, PHP 7 Example 2:php session_start(); if (isset($_SESSION['username'])) { echo "Welcome ".$_SESSION['username']."!"; } else { echo "Please login!"; } ``` This code checks whether the 'username' session variable is set or not. If it is set, it displays a welcome message. Otherwise, it asks the user to log in. Package Library: PHP 4, PHP 5, PHP 7 In summary, PHP Session isActive is a useful function for checking whether a session is active or not. It can be used in various applications that require session management, like user authentication, shopping carts, and more. The package library for this function depends on the PHP version being used.