Deep learning is a type of machine learning that uses neural networks with multiple layers between the input and output layers. It allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. Deep learning has achieved great success in computer vision, speech recognition, and natural language processing due to recent advances in algorithms, computing power, and the availability of large datasets. Deep learning models can learn complex patterns directly from large amounts of unlabeled data without relying on human-engineered features.