The liver is a large lobed glandular organ located in the upper right side of the abdominal cavity beneath the diaphragm. It has both excretory and secretory functions and is the largest gland in the body. The liver is reddish-brown due to breakdown of hemoglobin and plays several important roles, including metabolic functions like breaking down carbohydrates, proteins, and fats, storage of nutrients, and production of bile and proteins. It is divided into four lobes - right, left, caudate, and quadrate.