Booleans (bools for short), are referred to as logical, because they either can be true or false. Booleans are used when you need to determine whether some logic is true or false. For example, did the user log in? This statement would either be true, yes, they did or false, no, they did not. So, in Playgrounds, add true and false:
So, now we covered all of the basic data types in Swift. Right now, we have no way to use these data types. This is where variables and constants come into play.