The motivation for deep neural networks (DNNs) is similar, and the question here is, instead of using one single hidden layer, what if we use many hidden layers? So in that case, our model will look similar to the following:
Here, we have the same input layer. However, in this case, we will have many hidden layers and the output layer will stay the same. The key thing here is the hidden part of the network, the hidden layers; instead of having just one, we have many hidden layers and this is called a DNN.