# Number of elements

The number of elements of a **finite** set $$A$$ is written as $$n(A)$$ or $$\vert A \vert$$. It is also called the cardinality of the set $$A$$.

A **subset** $$A$$ of a finite set $$B$$ is finite and has fewer elements than the set $$B$$. This can be written as $$$n(A)\le n(B).$$$

A proper subset of a finite set has fewer elements than the original set.