Null

The value null is a reference that does not refer to anything.

Related concepts:  ValueReference

Closest Wikipedia entry:  Null pointer — In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types and to the Nothing value in an option type. A null pointer should not be confused with an uninitialized pointer: a null pointer is guaranteed to compare unequal to any pointer that points to a valid object.

Misconceptions about Null

7 documented Misconceptions