Aleph (ℵ), unadorned with subscripts, is the common symbol for the cardinality of the continuum.

2^{ℵ0} = ℵ

With subscript 0, ℵ_{0} (aleph-null) is the cardinality of the integers. With successive (ordinal) subscripts, ℵ_{z} is the *z*'th cardinal after ℵ_{0}. The Continuum Hypothesis (CH) is that ℵ = ℵ_{1}.