This document provides an introduction to deep learning, including key developments in neural networks from the discovery of the neuron model in 1899 to modern networks with over 100 million parameters. It summarizes influential deep learning models such as AlexNet from 2012, ZF Net and GoogLeNet from 2013-2015, which helped reduce error rates on the ImageNet challenge. Top AI scientists who have contributed significantly to deep learning research are also mentioned. Common activation functions, convolutional neural networks, and deconvolution are briefly explained with examples.