In historical linguistics, a chain shift is a set of sound changes in which the change in pronunciation of one speech sound (typically, a phoneme) is linked to, and presumably causes, a change in pronunciation of other sounds as well. The sounds involved in a chain shift can be ordered into a "chain" in such a way that after the change is complete, each phoneme ends up sounding like what the phoneme before it in the chain sounded like "before" the change. The changes making up a chain shift, interpreted as rules of phonology, are in what is termed "counterfeeding order".