Tariff
A tariff is a tax on imports or exports between sovereign states. It is a form of regulation of foreign trade. It is a policy that taxes foreign products to encourage or protect domestic industry. It helps limit trade deficits. The tariff is historically used to protect infant industries and to allow import substitution industrialization.
Protectionism in the United States
All tariffs were on a long list of goods (dutiable goods) with different customs rates and some goods on a "free" list. Congress spent enormous amounts of time figuring out these tariff import tax schedules.