An [[Infinity|Infinite]] [[Set]] is a set with a non-[[Finite|finite]] [[Cardinality]]. ### Countable Sets If there exists a [[Bijective|Bijection]] between a [[Set]] $A$ and $\Z^{+}$, $A$ is called [[Infinite Set|Countable]]. $\huge |A| = |\Z^{+}| = \aleph_{0} $