PHP Security Basics

Relax. We'll talk through this in plain words — no textbook voice.

When learning PHP, security shouldn't be something you leave for last. Right from the beginner stage, you need to build habits like never trusting user input, escaping output, using prepared statements in database queries, and hashing passwords. Bolting security on later is like building the house first and only then installing the door.

php

<?php
// Output escaping example
$userName = $_POST["name"] ?? "Guest";
echo "Hello, " . htmlspecialchars($userName, ENT_QUOTES, "UTF-8");

// Password hashing example
$password = "my-secret-password";
$hash = password_hash($password, PASSWORD_DEFAULT);

if (password_verify($password, $hash)) {
  echo "<br>Password is valid.";
}
?>

You should see

Displays the escaped username and the text "Password is valid."

Easy traps

Don't use md5() or sha1() for password storage. Use password_hash() instead.