Unlike local variables, a global variable can be accessed in any part of the program.
If we want a variable to be accessible from within a function, we can use the global keyword.
Global Variable can be accessed anywhere in our script, whether inside or outside a function.
In order to modify a global variable, it must be explicitly declared to be global in the function
in which it is to be modified.
Superglobals are built-in variables which are always available in all scopes throughout the script
and hence it is not required to declare global $variable to access them within functions or methods.
These superglobal variables are:
(1) $GLOBALS - It references all variables available in global scope.