PHP in a Nutshell

Superglobals

Variables that come into PHP arrive inside one of several special arrays known collectively as the superglobals , so named because they are available throughout your script, even inside objects and other arrays. Superglobals include form data sent from your visitor, cookie data, session information, local server information, and more, making them good to keep around. Superglobals were not available in PHP prior to v4.1, but there were older alternatives that provided much of the functionality. Superglobals are superior, though, so it is recommended that all new scripts use them.

There are nine superglobal arrays available for use, categorized by type of variable. These are shown in Table 5-2.

Table 5-2. The superglobal arrays

Name	Functionality
$_GET	Contains all variables sent via a HTTP GET request. For example, a URL of myfile.php?name=Paul would load myfile.php and give you $_GET["name"] with the value "Paul". Users of older PHP versions will have used $HTTP_GET_VARS array, which, although deprecated, is still available for use.
$_POST	Contains all variables sent via a HTTP POST request. This is similar to the old $HTTP_POST_VARS array, which, although deprecated, is still available for use.
$_FILES	Contains all variables sent via a HTTP POST file upload. This is similar to the old $HTTP_POST_FILES array, which is also deprecated.
$_COOKIE	Contains all variables sent via HTTP cookies. This is similar to the old $HTTP_COOKIE_VARS array, which is ...