In this chapter the processes involved in the practice of anesthesia and the associated common adverse events are described. Anesthesia is the discipline of pain relief. Pain may result from many different causes but the nonanesthetist immediately links the anesthesiologist with the relief of pain during surgery. Indeed, the relief of pain during surgery has made all the advances in surgery possible. It is therefore true to say that surgery stands on the shoulders of anesthesia. In this chapter the process of anesthesia is discussed and some of the common difficulties which may lead to litigation explained. Pain relief during surgery may be provided by general or regional anesthesia or by a combination of both.