What does null mean? [duplicate]

Answer 1

1. Null means nothing. No object. At all. A null value can be assigned to an object reference of any type.

2. Null can be cast to any type as it can be assigned to an object reference of that type. It, in a way, can act as every type, except for the fact that it is useless when trying to do field/method access(where a NullPointerException will be thrown) and is not every type. Note that null instanceof Foo is always false, no matter what foo is.