A set partition is a way of dividing a set into non-empty, disjoint subsets, where each element of the original set belongs to exactly one subset. For example, if we have a set A, B, C, one possible partition could be {A, B, C}. Each subset in the partition is called a block, and the collection of blocks together covers all elements of the original set without overlap. Set partitions are important in various fields, including combinatorics and mathematics, as they help in organizing data and solving problems related to grouping. The number of different ways to partition a set is given by the Bell number, which grows rapidly with the size of the set.