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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.

PHP Manual