In the previous chapter, we presented the classic hypergeometric functions that constitute the functions associated with the integer order calculus, in particular, a generalization of the factorial concept by the gamma function. In a similar way, we can understand why fractional calculus is an important tool for refining the description of many natural phenomena, particularly those with temporal dependence, where the called memory effect becomes present, from the understanding of form that the functions related to it generalize the functions relative to the integer order calculus.