 The most obvious feature is a substantial increase in the number of hidden layers. Whereas Golden Age networks typically had only one or two hidden layers, deep neural nets have anywhere from five to several hundred. It has been proven that additional depth can exponentially increase the representational and computational power of a neural network, compared to a shallower network with the same number of nodes (Bengio &amp; Dellaleau 2011; Montúfar et al. 2014; Raghu et al. 2017). The key is that the patterns detected at a given layer may be used by the subsequent layers to repeatedly create more and more complex discriminations.