Global Values of Symbols
Symbols are normally grouped into packages. A package represents a mapping between a set of symbols and their various bindings within the package.
In simple programs, we can usually ignore the fact that there are different packages.
> (setq x 5) ; What’s going on here?
X is a symbol which is registered (“interned”) in the current package. Its global value (“symbol value”) has been set to 5. Its symbol-value binding has indefinite extent. It has global scope.