Predefined Variables

PHP provides a large number of predefined variables to any script that it runs. These variables are superglobals, which are available anywhere in a script. Here's a list of the primary ones:

• $_GLOBALS. Contains every variable that is currently available within the global scope of the script. The keys of this array are the names of the global variables.

• $_SERVER. Variables set by the web server or otherwise directly related to the execution environment of the current script.

• $_GET. Variables provided to the script via HTTP GET.

• $_POST. Variables provided to the script via HTTP POST.

• $_COOKIE. Variables provided to the script via HTTP cookies.

• $_FILES. Variables provided to the script via HTTP POST file uploads.

• $_ENV. Variables provided to the script via the environment.

• $_REQUEST. Variables provided to the script via the GET, POST, and COOKIE input mechanisms.

• $_SESSION. Variables that are currently registered to a script's session.