How do hidden fields and session data play a role in managing complex form submissions in PHP?

Hidden fields and session data can be used to store temporary information or data that needs to persist across multiple form submissions. Hidden fields can be included in the form to store data that should not be visible to the user but needs to be sent along with the form submission. Session data can be used to store information that needs to be accessed across different pages or requests. By utilizing hidden fields and session data, developers can effectively manage complex form submissions in PHP.

<?php
session_start();

// Set session data
$_SESSION['temp_data'] = 'Some temporary data';

// HTML form with hidden field
echo '<form method="post" action="process_form.php">
    <input type="hidden" name="hidden_field" value="Hidden value">
    <input type="text" name="input_field">
    <input type="submit" value="Submit">
</form>';
?>