What is an RNN?
Recurrent neural networks (RNN) are the state of the art algorithm for sequential data and are used by Apple’s Siri and and Google’s voice search. 
RNNS remember their input due to an internal memory, making them perfect for learning problems involving sequential data like time series, speech, text, financial data, audio, video, weather and much more. 
Derived From Feedforward Networks
Derived from feedforward networks, RNNs exhibit similar behavior to how human brains function.