Deep learning is a subfield of machine learning that involves training artificial neural networks to recognize and classify patterns in large datasets. These neural networks are inspired by the structure and function of the human brain, and are composed of multiple layers of interconnected nodes or "neurons". By adjusting the strength of connections between neurons, deep learning algorithms can learn to extract complex features from raw data, such as images, speech, or text. This has led to breakthroughs in a wide range of fields, including computer vision, natural language processing, speech recognition, and robotics. Deep learning has also enabled the development of cutting-edge applications such as self-driving cars, personalized medicine, and virtual assistants.