Deep Neural Networks History: https://arxiv.org/abs/1701.05549v1 [PDF]
DNN are one of the most efficient tools that belong to a broader area called deep learning. DNN process input information in a hierarchical way, where each subsequent level of processing extracts more abstract /global / invariant features. In other words, DNN (semi) automatically learn key features from data and then aggregate them for some purpose, such as recognizing objects in the images.
