This document provides an overview of deep learning. It defines deep learning as a subset of machine learning that uses neural network architectures, especially deep neural networks containing many hidden layers. Deep learning models are trained on large labeled datasets to automatically extract features without manual feature engineering. Convolutional neural networks are commonly used for tasks like image classification by extracting hierarchical features from images. The document outlines the basic architecture of CNNs including convolutional layers that extract features and pooling layers that reduce size, as well as fully connected layers. It also briefly describes the learning process of forward and backward propagation.