Tariff
A tariff is called an optimal tariff if it's set to maximize the welfare of the country imposing the tariff. It is a tariff derived by the intersection between the "trade indifference curve" of that country and the offer curve of another country. In this case, the welfare of the other country grows worse simultaneously, thus the policy is a kind of "beggar thy neighbor policy". If the offer curve of the other country is a line through the origin point, the original country is in the "condition of a small country", so any tariff worsens the welfare of the original country.
Tariff
The tariff has been used as a political tool to establish an independent nation; for example, the United States Tariff Act of 1789, signed specifically on July 4, was called the "Second Declaration of Independence" by newspapers because it was intended to be the economic means to achieve the political goal of a sovereign and independent United States.