How can PHP beginners avoid security vulnerabilities in their code?

PHP beginners can avoid security vulnerabilities in their code by following best practices such as validating user input, using parameterized queries to prevent SQL injection, escaping output to prevent cross-site scripting attacks, and keeping PHP and its libraries up to date to patch any known security vulnerabilities. 

// Example of validating user input to prevent SQL injection
$username = mysqli_real_escape_string($conn, $_POST['username']);
$password = mysqli_real_escape_string($conn, $_POST['password']);

$query = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = mysqli_query($conn, $query);

Keywords

SQL injection cross-site scripting input validation secure coding practices password hashing.

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