The empty set, Ø, is the set that has no members.

The set with no elements.

Also called the null set, the empty set is the set that contains no elements.

A finite set that contains no elements.

In mathematics and more specifically set theory, the empty set is the unique set which contains no elements. In axiomatic set theory it is postulated to exist by the axiom of empty set and all finite sets are constructed from it. The empty set is also sometimes called the null set, but because null set means something else in measure theory, that term is generally avoided in current work.