Gallstones are solid particles that form in the gallbladder, a small organ located beneath the liver. They can vary in size from tiny grains to large stones and are primarily made of cholesterol or bilirubin. Gallstones can block the bile ducts, leading to pain and digestive issues. Many people with gallstones experience no symptoms, but when symptoms occur, they may include sharp abdominal pain, nausea, and vomiting. Treatment options range from dietary changes to surgical removal of the gallbladder in more severe cases. Regular check-ups can help monitor gallstone-related health.