Here is the beginning of the article on the British National Health Service's website:
Gallstones are small stones, usually made of cholesterol, that form in the gallbladder. In most cases they do not cause any symptoms and do not need to be treated.
However, if a gallstone becomes trapped in a duct (opening) inside the gallbladder it can trigger a sudden intense abdominal pain that usually lasts between one and five hours. This type of abdominal pain is known as biliary colic.
The medical term for symptoms and complications related to gallstones is gallstone disease or cholelithiasis.