Predefined variables

The predefined variable PHP_SELF outputs the filename of the current script relative to the root.
The output of this variable is: /infost440/a3/predefined.php
The predefined variable GATEWAY_INTERFACE outputs the CGI specification of the current server.
The output of this variable is: CGI/1.1

Predefined variables provide information about the execution environment. Some predefined variables are called superglobals which are automatically available in every scope.
Predefined variables are numerous in number, allow output of important and frequently used information.