PHP Predefined Variables

Predefined Variable 1: $_SERVER['PHP_SELF']

Current script path: /infost440/a3/predefined.php

This variable holds the filename and path of the currently executing script.

Predefined Variable 2: $_SERVER['SERVER_NAME']

Server name: plummerj.soisweb.uwm.edu

This variable holds the name of the host running the current script.

Explanation

Predefined variables are made by PHP automatically for every script so you don't declare them yourself as they are already there e.g., $_SERVER, and it holds a lot of pieces of information about the server and the current page