Machine learning is a subset of artificial intelligence that uses algorithms and data to gradually improve accuracy. There are several types of machine learning including supervised learning, which uses labeled training data; unsupervised learning, which finds patterns without labels; and reinforcement learning, which uses trial-and-error. Machine learning has many applications such as image classification, customer segmentation, and fraud detection. It provides benefits like accuracy, automation, and scalability but also has limitations such as potential bias if the training data is biased.