How many languages exist over the following alphabets?
A language over an alphabet $\Sigma$ is any subset of the set of all finite strings with elements in $\Sigma$. If $\Sigma$ is finite or countably infinite, and not empty, then the set of all finite strings with elements in $\Sigma$ is countably infinite ($\aleph_0$) and the set of all languages over the alphabet $\Sigma$ has the same cardinality as the real numbers ($\aleph_1$). (Not calling it just "uncountable", because the set of languages is indeed uncountable, but there are uncountable sets with higher cardinality).