superglobals in php with explain with output

Some predefined variables in PHP are "superglobals", which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.

$x=10;

echo $_GLOBALS['x']; // access global variables because all variables are global

• $_SERVER: Contains information about the server and environment, such as the URL, HTTP headers, and script location.
• $_GET: Contains variables passed to the current script via the URL parameters.
• $_POST: Contains variables submitted via an HTML form using the HTTP POST method.
• $_FILES: Contains information about files uploaded via an HTML form using the HTTP POST method.
• $_COOKIE: Contains variables stored in the user's browser cookies.
• $_SESSION: Contains variables that are specific to the current user's session.
• [OPENSSL_CONF] => C:/xampp/apache/bin/openssl.cnf
• [TMP] => \xampp\tmp  
• [HTTP_HOST] => localhost
• [HTTP_CONNECTION] => keep-alive
• [HTTP_USER_AGENT] => Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.90 Safari/537.36 

• [HTTP_ACCEPT] => text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,application/signed-exchange;v=b3

• [HTTP_COOKIE] => _ga=GA1.1.1951352871.1571924619;
• [SystemRoot] => C:\Windows
• [COMSPEC] => C:\Windows\system32\cmd.exe
• [PATHEXT] => .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
• [WINDIR] => C:\Windows
• [SERVER_NAME] => localhost   
• [SERVER_ADDR] => ::1
• [SERVER_PORT] => 80
• [REMOTE_ADDR] => ::1
• [DOCUMENT_ROOT] => C:/xampp/htdocs
• [REQUEST_SCHEME] => http
• [SCRIPT_FILENAME] => C:/xampp/htdocs/test.php
• [REMOTE_PORT] => 62305
• [SERVER_PROTOCOL] => HTTP/1.1
• [REQUEST_METHOD] => GET
• [QUERY_STRING] =>
• [REQUEST_URI] => /test.php
• [SCRIPT_NAME] => /test.php
• [PHP_SELF] => /test.php
• $_REQUEST['nameOfFormField'];   // get form data
• $_POST['fieldName'];// if form method is post
• $_GET['fieldName'];// get form data if method is get
• $_FILES //handle files upload etc
• print_r($_COOKIE); //cookies
• $_SESSION //sessions