What are some best practices for securely handling form data in PHP scripts?

When handling form data in PHP scripts, it is crucial to sanitize and validate the input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. One best practice is to use PHP's filter_input function to sanitize user input and validate it against expected data types. Additionally, you should always use prepared statements when interacting with a database to prevent SQL injection attacks.

// Sanitize and validate form data using filter_input
$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);

// Use prepared statements to interact with the database
$stmt = $pdo->prepare("INSERT INTO users (username, email) VALUES (:username, :email)");
$stmt->bindParam(':username', $username);
$stmt->bindParam(':email', $email);
$stmt->execute();