In number theory and combinatorics, a partition of a positive integer $n$ is a way of writing $n$ as a sum of positive integers. Two sums that differ only in the order of their summands (also called parts) are considered the same partition. For example, all of the partitions of $4$ are $1 + 1 + 1 + 1$, $2 + 1 + 1$, $2 + 2$, $3 + 1$, or $4$.
The number of partitions of $n$ is given by the partition function $p(n)$. For the example above, $p(4) = 5$.
Partitions can be visualized graphically with Ferrers diagramsFerrers diagrams.
Partitions have applications in symmetric polynomials, the symmetric group, and group representations.