Recurrent Neural Network

Suppose we have a sentence and we have to predict whether the sentence is positive or negative, we can do it with the help of RNN. Time series data, stock fore-casting, Spam Classifier is where RNN is extensively used. Before we deep dive into neural network, lets mull over why do we need to deal with the sequential neural network? What we can obtain using neural network with sequences? Lets take an example of Spam classifier, we pass an input text data to the model.