Scope is the set of variables you have access to
As we learned in the beginning of this class, JavaScript reads from top to bottom
Sometimes, however, we declare variables inside functions (just like arguments), which aren’t accessible in other parts of our code; this is the concept of scope.
A variables scope is determined primarily based on where is was declared
Variables declared inside a function are in local scope
Variables defined outside of a function are in the global scope
Each function when invoked creates a new scope