currency substitution

The practice by the citizenry of a country to hold the currency of a foreign country in addition to its domestic currency as a store of value or as an additional medium of exchange. Historically, governments and citizens of developing countries have turned to foreign currencies, primarily the U.S Dollar, as a substitute for their declining currencies. This typically resulted in increased volatility of their currencies exchange rate making it difficult for their central banks to intervene with stabilizing monetary policies.