Gallstones are little pebble-like substances that form in the gallbladder, a small organ located under the liver that helps with digestion. These stones develop because cholesterol and pigments in bile sometimes form hard particles. You may have a gallstone and not know it. When symptoms do occur, you may have stomach and back pain, feel nauseous, and may vomit. If you have symptoms of gallstones, it is important to tell your doctor to prevent serious problems from developing. Follow the links below to find WebMD's comprehensive coverage about gallstones andgallbladder problems, including what gallstones look like, how they are treated, and much more.