PHP Superglobal Variables
Superglobals are built-in arrays accessible from any scope. They contain information about the request, server, and session.
Example
<?php
// $_GET — query string parameters
// URL: page.php?name=Alice&age=25
$name = $_GET['name'] ?? 'Guest';
$age = $_GET['age'] ?? 0;
// $_POST — form data (POST method)
$email = $_POST['email'] ?? '';
// $_REQUEST — combines GET, POST, COOKIE
$value = $_REQUEST['key'] ?? 'default';
// $_SERVER — server and request info
echo $_SERVER['REQUEST_METHOD']; // GET, POST, etc.
echo $_SERVER['HTTP_HOST']; // domain name
echo $_SERVER['REMOTE_ADDR']; // client IP
echo $_SERVER['DOCUMENT_ROOT']; // server path
// $_FILES — uploaded files
// $_SESSION — session data
// $_COOKIE — cookies
// $_ENV — environment variables
?>