This document provides an overview of deep learning, including conceptual understanding and applications. It defines deep learning as a deep and wide artificial neural network. It describes key concepts in artificial neural networks like signal transmission between neurons, graphical models, linear/logistic regression, weights/biases/activation, and backpropagation. It also discusses popular deep learning applications and techniques like speech recognition, natural language processing, computer vision, representation learning using restricted Boltzmann machines and autoencoders, and deep network architectures.