A subset is a set that contains some or all elements of another set. For example, if we have a set A, B, C, the subsets could include A, B, C, and even the empty set {}. The original set itself is also considered a subset, so A, B, C is a subset of itself. In mathematics, subsets are important for understanding relationships between sets. The concept helps in various fields, including statistics, probability, and combinatorics. Subsets can be classified as proper subsets, which do not include all elements of the original set, or improper subsets, which do.