How can beginners improve their understanding of PHP fundamentals to avoid common pitfalls when writing scripts for user authentication?

Beginners can improve their understanding of PHP fundamentals by studying the basics of user authentication, including hashing passwords securely, validating user input, and implementing proper error handling. Additionally, they should practice writing test cases to ensure their authentication scripts work as intended and avoid common pitfalls such as SQL injection vulnerabilities.

// Example code snippet for securely hashing passwords in PHP
$password = "password123";
$hashed_password = password_hash($password, PASSWORD_DEFAULT);