What are some potential pitfalls to be aware of when passing data between pages in a PHP form?

One potential pitfall when passing data between pages in a PHP form is the risk of data manipulation or injection by malicious users. To prevent this, it is important to sanitize and validate user input before passing it to the next page. Additionally, using sessions or cookies to store and retrieve data securely can help maintain the integrity of the data being passed.

// Sanitize and validate user input before passing it to the next page
$user_input = filter_var($_POST['user_input'], FILTER_SANITIZE_STRING);

// Store the sanitized input in a session variable
session_start();
$_SESSION['user_input'] = $user_input;

// Redirect to the next page
header("Location: next_page.php");
exit();