A token is the smallest component of a source script text that can be interpreted.
Tokens are the actual components that an executable script is built from. They may be reserved words, identifiers, punctuator symbols or literals.
You cannot use reserved words as identifier names.
The reserved word set is comprised of the structural statements that you use to make a script work.
The null literal is simply the keyword null.
The Boolean literals are the keywords true and false.
See the reserved words topic for a list of all currently defined reserved words.