Predefined variables
PHP Manual

Superglobals

SuperglobalsSuperglobals are built-in variables that are always available in all scopes

Description

Several predefined variables in PHP are "superglobals", which means they are available in all scopes throughout a script. There is no need to do global $variable; to access them within functions or methods.

These superglobal variables are:

ChangeLog

Version Description
4.1.0 Superglobals were introduced to PHP.

Notes

Note: Variable availability
By default, all of the superglobals are available but there are directives that affect this availability. For further information, refer to the documentation for variables_order.

Note: Dealing with register_globals
If the deprecated register_globals directive is set to on then the variables within will also be made available in the global scope of the script. For example, $_POST['foo'] would also exist as $foo.
For related information, see the FAQ titled "How does register_globals affect me?"

Note: Variable variables
Superglobals cannot be used as variable variables inside functions or class methods.

See Also


Predefined variables
PHP Manual