In VB, we have only nothing, what translates to Default(of T).
Sometimes, this is a pain in the *** and we need a read NULL.
An example of usage:
Dim x = if(MyBool, True, Nothing)
Returns a Boolean, because nothing will translate to False
With the introduction of Null, we can write:
Dim x = if(MyBool, True, Null)
And this will return a nullable Boolean.