The term ＇subsidy＇ has been subject to many interpretations and much misuse, especially as regards energy subsidies. In common parlance a subsidy is a payment or tax concession from the government. Corden (1966) extended the concept to include in addition market transfers - that is, transfers from consumers to producers (or vice versa) resulting from government interventions that distort prices, such as tariffs or price controls. Several summary measures have been developed to indicate the level of subsidy provided by various instruments affecting a particular sector or activity.