A Bell Number is a special number in combinatorics that represents the number of ways to partition a set into non-empty subsets. For example, the first few Bell Numbers are 1, 2, 5, 15, and 52, corresponding to the partitions of sets with 0, 1, 2, 3, and 4 elements, respectively. These numbers are named after the mathematician Eric Temple Bell, who studied them in the early 20th century. Bell Numbers can be calculated using various methods, including Stirling numbers and recursive formulas, making them an important concept in the study of set theory and combinatorial mathematics.