Deep learning is a subset of machine learning that involves artificial neural networks with multiple layers (deep neural networks). It's inspired by the structure and function of the human brain's interconnected neurons. In retail, deep learning is applied to various tasks, such as image and speech recognition, natural language processing, and recommendation systems. Retailers use deep learning algorithms to analyze vast amounts of data, make predictions, and personalize customer experiences. For instance, deep learning is employed in product recommendation engines, fraud detection, and demand forecasting, enhancing operational efficiency and providing a more tailored shopping experience for customers.