Have you ever wondered how predictive text algorithm works? How exactly does that speech recognition software know our voice? As for image classification, convolutional neural networks were turning the whiles behind the scene, for these kinds of problems we are using Recurrent Neural Networks (RNN). These Neural Networks are very powerful and they are especially useful in so-called Natural Language Processing (NLP). One might wonder what makes them so special.Well, the networks we examined so far, Standard Neural Networks and Convolutional Neural Networks, are accepting a fixed-size vector as input and produce a fixed-sized vector as an output.