# Uncountability

Sizes of in­finity fall into two broad classes: countable in­fini­ties, and un­countable in­fini­ties.

A set $$S$$ is un­countable if it is not countable.

Children:

Parents:

• Mathematics

Math­e­mat­ics is the study of num­bers and other ideal ob­jects that can be de­scribed by ax­ioms.