Herring are small, silvery fish that live mainly in the shallow waters of the North Atlantic and North Pacific oceans. They belong to the genus Clupea and are known for swimming in large groups called schools. Herring are an important part of the marine food chain, serving as food for larger fish, seabirds, and marine mammals. They feed mostly on plankton and small crustaceans. They are also commercially valuable and widely eaten around the world—often smoked, salted, or pickled. Popular types include the Atlantic herring and Pacific herring.  Overall, herring are essential both ecologically and economically.