What are common methods for passing login data between PHP programs?

One common method for passing login data between PHP programs is by using sessions. Sessions allow you to store user login information securely on the server and access it across different pages within the same session. Another method is using cookies to store login data on the client side, but this method may not be as secure as sessions.

// Start a session
session_start();

// Set login data in session variables
$_SESSION['username'] = 'example_username';
$_SESSION['email'] = 'example_email@example.com';

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

// Destroy the session when the user logs out
session_destroy();