Functional programming is a programming paradigm that focuses on using functions to perform computations. It emphasizes immutability and avoids changing state or mutable data. In functional programming, functions are treated as first-class citizens, meaning they can be assigned to variables, passed as arguments, and returned as results. This approach allows for code that is concise, modular, and easier to reason about. Therefore, the term "What"-oriented programming is most closely associated with functional programming.