What best practices should be followed when using sessions in PHP for form data?

When using sessions in PHP for form data, it is important to follow best practices to ensure the security and reliability of the data being stored. One important practice is to always sanitize and validate user input before storing it in the session to prevent any potential security vulnerabilities. Additionally, make sure to regenerate the session ID after a successful login to prevent session fixation attacks. Lastly, remember to unset or destroy the session data once it is no longer needed to free up server resources.

// Start the session
session_start();

// Sanitize and validate user input
$clean_data = filter_input_array(INPUT_POST, FILTER_SANITIZE_STRING);

// Store sanitized data in session
$_SESSION['form_data'] = $clean_data;

// Regenerate session ID after successful login
if ($user_authenticated) {
    session_regenerate_id(true);
}

// Unset or destroy session data when it is no longer needed
unset($_SESSION['form_data']);
// or session_destroy();