What are the best practices for handling form data in PHP scripts, especially in relation to user authentication and authorization?

When handling form data in PHP scripts, especially for user authentication and authorization, it is important to sanitize and validate the input to prevent SQL injection and other security vulnerabilities. Additionally, always use prepared statements when interacting with a database to prevent SQL injection attacks. It is also recommended to use password hashing functions like password_hash() and password_verify() for securely storing and verifying passwords.

// Sample code for handling user authentication and authorization in PHP

// Sanitize and validate form input
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);
$password = filter_var($_POST['password'], FILTER_SANITIZE_STRING);

// Hash the password
$hashed_password = password_hash($password, PASSWORD_DEFAULT);

// Verify password
if (password_verify($password, $hashed_password)) {
    // Password is correct, proceed with authentication
    // Check user credentials in the database
} else {
    // Password is incorrect, handle accordingly
}