$_REQUEST
$_ENV
Predefined variables
PHP Manual

# $_SESSION

# $HTTP_SESSION_VARS [deprecated]

$_SESSION -- $HTTP_SESSION_VARS [deprecated] — Session variables

### Description

An associative array containing session variables available to the current script. See the Session functions documentation for more information on how this is used.

$HTTP_SESSION_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_SESSION_VARS and $_SESSION are different variables and that PHP handles them as such)

### Changelog

Version | Description
--- | ---
4.1.0 | Introduced $_SESSION that deprecated $HTTP_SESSION_VARS.

### Notes

> Note: This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.

### See Also

- session_start()

$_REQUEST
$_ENV
Predefined variables
PHP Manual