- a scope can be imagined as a region
- local scope = var which is defined inside a function can only be used inside that function
- global scope = vars which are created outside a function are part of the global scope and can be used within any scope
a can be used inside the function (local scope). However, b,c and d aren’t defined in the global scope. If you would try to print b outside of the function the computer wouldn’t know what you mean, because it isn’t defined.