Gobstoppers or jawbreakers are a type of hard candy. They are usually round, and normally range from about 1–3 cm (0.39–1.18 in) across; though gobstoppers can be up to 8 cm (3.1 in) in diameter. The term gobstopper derives from "gob", which is slang in the United Kingdom and Ireland for mouth. The sweet was a favourite amongst British schoolboys between World War I and World War II. In his 1964 children's book Charlie and the Chocolate Factory, British author Roald Dahl described "Everlasting Gobstoppers", a fictional type of gobstopper that could never get smaller or be finished.
Gobstoppers usually consist of a number of layers, each layer dissolving to reveal a differently coloured (and sometimes differently flavoured) layer, before dissolving completely. Gobstoppers are too hard to bite without risking dental damage (hence the name jawbreaker).
Gobstoppers have been sold in traditional sweet shops for at least a century, often sold by weight from jars. As gobstoppers dissolve very slowly, they last a very long time in the mouth, which is a major factor in their enduring popularity with children. Larger ones can take days or even weeks to fully dissolve.