Cholelithiasis is the medical term for the formation of gallstones in the gallbladder. These stones can be composed of cholesterol, bilirubin, or a combination of both, and they can vary in size. Symptoms may include abdominal pain, nausea, and digestive issues, particularly after eating fatty meals. In some cases, gallstones can lead to complications such as cholecystitis or pancreatitis if they block the bile ducts.