Bile (or gall) is a dark green to brownish fluid produced by the liver and stored in the gallbladder (a small green hollow organ between the liver and the small intestines). Bile, that is consistent of so-called bile salts (anions of the steroid-derived bile acids), acts as a surfactant to bind and excrete fats, but also many liver metabolites of drugs, into the gastrointestinal system.