Deep Neural Networks represent a cornerstone of modern artificial intelligence, particularly in tasks requiring the extraction of intricate patterns and features from data. Unlike shallow neural networks that might have just one hidden layer, DNNs consist of many layers, each capable of learning different levels of abstraction. This hierarchical learning approach allows DNNs to effectively handle high-dimensional data across various domains, including image and speech recognition, natural language processing, and even playing complex games. The depth of these networks significantly enhances their learning capacity, enabling the capture of complex representations without manual feature engineering. Training DNNs often involves backpropagation and requires substantial computational resources, especially for adjusting the large number of parameters involved.

The concept of deep neural networks dates back to the 1960s, with notable advancements in the 1980s through the introduction of backpropagation. However, they did not gain significant popularity until the late 2000s and early 2010s, when improvements in computational power, data availability, and algorithmic innovations (such as dropout and ReLU activations) made training deep networks more feasible.

Geoffrey Hinton, Yoshua Bengio, and Yann LeCun are often credited as key figures in the development and popularization of deep learning techniques, including DNNs. Their contributions have laid the groundwork for many of the advancements in artificial intelligence over the past two decades.