This presentation provides an introduction to machine learning in optical communication. It defines machine learning as algorithms that improve performance through experience and data observation. It describes traditional programming versus machine learning approaches. It then outlines several machine learning algorithms including supervised learning, unsupervised learning, semi-supervised learning, and reinforcement learning. It provides examples of how these algorithms could be applied in optical networks for tasks like quality of transmission estimation, optical amplifier control, modulation format recognition, nonlinearities mitigation, traffic prediction, and flow classification.