Yellow bile is one of the four bodily humors in ancient Greek medicine, believed to be produced by the liver. It was thought to be associated with the element of fire and was linked to a person's temperament, particularly the choleric personality, which is characterized by ambition and leadership. In historical medical practices, an imbalance of yellow bile was thought to cause various health issues, including anger and digestive problems. This concept was part of the broader theory of humoral medicine, which also included blood, phlegm, and black bile as key components influencing health and personality.