ℵ 0

Aleph-Null or ℵ 0 is the cardinality of the set of all natural numbers, and is an infinite cardinal. The set of all finite ordinals.

In Mathematics
the aleph numbers are a sequence of numbers used to represent the cardinality (or size) of infinite sets that can be well-ordered. They were introduced by the mathematician Georg Cantor and are named after the symbol he used to denote them, the Hebrew letter aleph.