:For other uses of this word, see tariff (disambiguation). A tariff's a duty imposed on goods when they're moved across a political boundary. They're usually associated with protectionism, the economic policy of restraining trade between nations. For political reasons, tariffs are usually imposed on imported goods, although they may also be imposed on exported goods. History In the past, tariffs formed a much larger part of government revenue than they do today. When shipments of goods arrive at… (More on Tariff)