Explain superglobals in php.

 Q. Explain superglobals in php.
Answer:
Superglobals in PHP are special arrays that are automatically available in all scopes of a script. They provide global access to certain variables, enabling developers to access and manipulate information across different parts of their script without the need for explicit declarations.

Here are some commonly used PHP superglobals:

$_GET: Contains data sent to the script via URL query parameters (HTTP GET method).
$id = $_GET['id'];

$_POST: Contains data sent to the script via HTTP POST method (e.g., form submissions).
$username = $_POST['username'];

$_REQUEST: Combines the data from $_GET, $_POST, and $_COOKIE. Use with caution due to potential security risks.
$value = $_REQUEST['value'];

$_FILES: Contains information about file uploads via HTTP POST.
$file_name = $_FILES['file']['name'];

$_COOKIE: Contains data sent to the script via HTTP cookies.
$user_id = $_COOKIE['user_id'];

$_SESSION: Allows you to store and retrieve values across multiple requests within a user's session.
session_start();
$_SESSION['user_id'] = 123;

$_SERVER: Contains information about the server and the execution environment.
$server_name = $_SERVER['SERVER_NAME'];

$_ENV: Contains environment variables.
$user_home = $_ENV['HOME'];

$GLOBALS: Represents all global variables.
function example() {
    $GLOBALS['global_var'] = 'Hello';
}

example();
echo $global_var;  // Outputs: Hello

Superglobals are always accessible, regardless of scope. They are automatically populated by PHP, and changes made to them in one part of the script are reflected in all other parts. It's essential to handle user input from superglobals with care to avoid security vulnerabilities such as SQL injection or cross-site scripting (XSS). Proper validation and sanitization should be applied to any data obtained from these sources.