When I started learning PHP, I thought security was something "advanced" developers worried about. I was wrong. Here are 5 mistakes I made in my first projects that almost got my clients hacked. If you're a PHP beginner in 2026, avoid these: 1. Trusting User Input - The #1 Sin ❌ Mistake: Using $_GET or $_POST directly in SQL queries. $id = $_GET['id']; mysql_query("SELECT * FROM users WHERE id = $id"); Why it's deadly: A hacker can type 1; DROP TABLE users-- in the URL and delete your whole database. This is called SQL Injection. Fix in 2026: Always use Prepared Statements with PDO. $stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?"); $stmt->execute([$id]); 2. Storing Passwords as Plain Text ❌ Mistake: Saving passwords directly like password123 in the database. Why it's deadly: If your database leaks, every user's password is exposed. Hackers will try that password on Gmail, Facebook, everything. Fix in 2026: Use password_hash() and password_verify() . PHP does the heavy lifting.…