Kleene's Theorem is a fundamental result in automata theory that establishes a connection between regular expressions and finite automata. It states that a language is regular if and only if there exists a finite automaton that recognizes it, and conversely, for every finite automaton, there is a regular expression that describes the same language. The theorem is named after Stephen Cole Kleene, who contributed significantly to the field of formal languages. It provides a framework for understanding how different representations of languages, such as regular expressions and deterministic finite automata (DFA), can be used interchangeably in computer science and mathematics.