Null
The value null is a reference that does not refer to anything.
Related concepts: ValueReference
Closest Wikipedia entry: Null pointer
Misconceptions about Null6 documented Misconceptions
Check YourselfNullIsObject — Java
null is an objectOutOfBoundsElementsAreNull — Java
Out-of-bounds array elements are nullThisCanBeNull — Java
this can be nullThisInConstructorIsNull — Java
In a constructor, this is nullNullAndUndefinedAreTheSame — JavaScript
The values null and undefined are the sameNullIsObject — JavaScript
null is an object