Value types are non-nullable. But they're also stack-allocated* and passed by value, so they're really only appropriate in certain cases. You can't use them a

Value types are non-nullable. But they're also stack-allocated* and passed by value, so they're really only appropriate in certain cases. You can't use them as general-purpose non-nullable objects. *In practice, though technically that bit's an implementation detail of Microsoft's run-time and not part of the language spec.