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.
Superglobal variables are:
$GLOBALS
$_SERVER
$_GET
$_POST
$_FILES
$_COOKIE
$_SESSION
$_REQUEST
$_ENV
*We will explain in detail about these superglobal variable in next post.