Gallstones are hardened deposits of digestive fluid that can form in your gallbladder. Your gallbladder is a small, pear-shaped organ on the right side of your abdomen, just beneath your liver. The gallbladder holds a digestive fluid called bile that's released into your small intestine. Gallstones range in size from as small as a grain of sand to as large as a golf ball.  Types of gallstones Cholesterol gallstones. Pigment gallstones