In the context of PHP usage, what are the best practices for handling data exchange between multiple windows in a web application?

When handling data exchange between multiple windows in a web application using PHP, one of the best practices is to use sessions to store and retrieve data. Sessions allow data to be persisted across different pages and windows for a specific user session. By using session variables, you can easily pass data between different parts of your application without the need for complex URL parameters or form submissions.

// Start the session
session_start();

// Set a session variable
$_SESSION['data'] = 'Hello, world!';

// Retrieve the session variable in another window
$data = $_SESSION['data'];

// Unset the session variable when it's no longer needed
unset($_SESSION['data']);