Colic is a term used to describe severe, often fluctuating pain in the abdomen that is caused by the intestine or other parts of the digestive tract undergoing spasms. It can occur in both adults and infants, with symptoms including intense crying, discomfort, and difficulty feeding in babies. In infants, colic is commonly referred to as excessive crying that lasts for more than three hours a day, three days a week, for three weeks or longer. While the exact cause of infant colic is not fully understood, it is believed to be related to factors such as digestive issues, sensitivity to stimuli, or an immature nervous system.