Set theory

**Set theory** is a fundamental branch of mathematical logic that studies collections of objects, known as sets. It provides the foundational language and tools for various fields of mathematics, allowing the rigorous definition of concepts such as numbers, functions, and relations. Set theory explores operations on sets, including union, intersection, and difference, as well as properties like membership, subsets, and cardinality. This area of mathematics is essential for understanding the structure and behavior of mathematical systems and underpins many theoretical and practical applications.