What is PHP?

PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open-source, server-side scripting language created in 1994 by Rasmus Lerdorf. PHP is embedded inside HTML and executed on the web server — the browser never sees PHP code, only the HTML it produces.

• Powers 75%+ of all websites with a known server-side language (WordPress, Facebook, Wikipedia, Slack, Etsy).
• Free, runs on every OS, integrates natively with MySQL / PostgreSQL / SQLite.
• Huge ecosystem: WordPress, Laravel, Symfony, Drupal, Joomla, Magento.
• Quick to learn — write a working dynamic page in 5 lines.

php Run in compiler
<?php
$name = "World";
echo "Hello, $name!";   // → Hello, World!
?>

The <?php … ?> tags mark the boundary between HTML and PHP code. Anything outside the tags is sent to the browser unchanged.