PHP Predefined variables

PHP provides a large number of predefined variables to all scripts. The variables represent everything from external variables to built-in environment 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
    * $_ENV — Environment variables
    * $_COOKIE — HTTP Cookies
    * $php_errormsg — The previous error message
    * $HTTP_RAW_POST_DATA — Raw POST data
    * $http_response_header — HTTP response headers
    * $argc — The number of arguments passed to script
    * $argv — Array of arguments passed to script