A Universal Set is a collection that contains all possible elements relevant to a particular discussion or problem. It serves as the foundation for set theory, where other sets are defined as subsets of the universal set. For example, if we are discussing numbers, the universal set might include all integers, rational numbers, and irrational numbers. In mathematical notation, the universal set is often represented by the symbol U. Any specific set, such as 1, 2, 3 or a, b, c, is considered a subset of the universal set. Understanding the universal set helps clarify relationships between different sets and their elements.