Predefined Variables

Superglobals
Superglobals are built-in variables that are always available in all scopes

$GLOBALS
References all variables available in global scope

$_SERVER
Server and execution environment information

$_GET
— HTTP GET variables

$_POST
— HTTP POST variables

$_FILES
— HTTP File Upload variables

$_REQUEST
— HTTP Request variables

$_SESSION
— Session variables

$http_response_header
— HTTP response headers

$_ENV
— Environment variables

$argv
— Array of arguments passed to script

$_COOKIE
— HTTP Cookies

$php_errormsg
— The previous error message

$HTTP_RAW_POST_DATA
— Raw POST data

$argc
— The number of arguments passed to script