The term "memory-bound function" has surfaced only recently and is used principally to describe a function that uses XOR and consists of a series of computations in which each computation depends on the previous computation. Whereas memory functions have long been an important actor in improving time complexity, memory-bound functions have seen far fewer applications. Recently, however, scientists have proposed a method using memory-bound functions as a means to discourage spammers from abusing resources, which could be a major breakthrough in that area.