HowToCodePage

PHP: getting started

How PHP runs on the server, mixing code with HTML, and the request/response model behind almost every classic website.

A server-side language

PHP executes on the server and sends the resulting HTML to the browser. The visitor never sees your source — only its output. That is the fundamental difference from JavaScript running in the page.

<?php
// everything between these tags runs on the server
$name = "world";
echo "Hello, " . $name;
💡
Never trust that PHP code is hidden: a misconfigured server can serve raw .php as text, exposing credentials. Keep secrets outside the web root.

Mixing PHP and HTML

<!DOCTYPE html>
<html>
<body>
  <h1><?php echo htmlspecialchars($title); ?></h1>
  <ul>
  <?php foreach ($items as $item): ?>
    <li><?= htmlspecialchars($item) ?></li>
  <?php endforeach; ?>
  </ul>
</body>
</html>

<?= $x ?> is shorthand for <?php echo $x; ?>. The alternative-syntax foreach (…): … endforeach; exists exactly so templates stay readable.

⚠️
Always wrap output in htmlspecialchars() when it contains user data. Skipping it is how reflected XSS happens.

Running it

php -v
php -S localhost:8000      # built-in dev server
php script.php             # run a CLI script
  • Use the built-in server for development only; production needs a real web server.
  • A file's name decides the entry point: index.php is the usual directory default.
  • Enable error display locally, and disable it in production while logging to a file.

FAQ

Is PHP still worth learning?
Yes. It powers a very large share of the web, and modern PHP (8.x) has strict types, typed properties, named arguments and a solid ecosystem.
echo or print?
Both output text; echo accepts several arguments and is marginally faster. print returns a value, so it can be used in expressions.

PHP arrays Forms, sessions and safety

Last refreshed 2026-09-17.