Superglobals – Superglobals are built-in variables that are always available in all scopes. Article is for list and meaning of PHP superglobals, What is superglobals in PHP, PHP special variables.
Several predefined variables in PHP are “superglobals”, which means they are available in all scopes throughout a script. They are always accessible and you can access them from any function, class or file without any special process.
superglobal variables are: