The Boolean type

Boolean is a logic type that has two possible values: true and false. We can also use the nullable Boolean type:

    val isGrowing: Boolean = true 
    val isGrowing: Boolean? = null 

The Boolean type also supports standard built-in operations that are generally available in most modern programming languages:

• ||: Logical OR. Returns true when any of two predicates return true.
• &&: Logical AND. Returns true when both predicates return true.
• !: Negation operator. Returns true for false, and false for true.

Keep in mind that we can only use a not-null Boolean for any type of condition.

Like in Java, in || and && predicates are evaluated lazily, and only when needed (lazy conjunction).