In the context of international trade, tariffs play a significant role as they are taxes imposed on imported goods. When a country implements tariffs, it effectively raises the cost of foreign products, which can hinder free trade by creating a barrier to entry for international suppliers. However, this practice also generates tax revenue for the government, which is one of the primary motivations for imposing tariffs.

To understand the impact of tariffs, consider the scenario where a country has a low world price for a product. This price leads to a situation where domestic supply is insufficient to meet consumer demand, resulting in a significant volume of imports. When a tariff is introduced, the effective price of imports increases, as it is now the world price plus the tariff amount. This adjustment allows domestic suppliers to become more competitive, as they can now supply more at the higher price, thereby reducing the volume of imports.

Graphically, the introduction of a tariff alters the equilibrium between quantity supplied and quantity demanded. The new quantity supplied increases, while the quantity demanded decreases, leading to a smaller amount of imports. This shift affects consumer surplus and producer surplus. Before the tariff, consumer surplus is maximized, but after the tariff is imposed, consumer surplus diminishes due to higher prices and reduced quantity demanded. Conversely, producer surplus increases as domestic producers benefit from the higher prices and are able to supply more.

Government revenue from tariffs is calculated based on the tariff amount multiplied by the quantity of imports. This revenue represents a transfer of surplus from consumers to the government. However, the imposition of tariffs also results in deadweight loss, which occurs when the tax prevents some mutually beneficial trades from occurring. In this case, the deadweight loss can be visualized as a "bridge" between the areas of lost consumer surplus and the gains in producer surplus, highlighting the inefficiencies introduced by the tariff.

Overall, the total surplus in the economy is affected by the tariff, as it reduces consumer surplus while increasing producer surplus and generating government revenue. The two main types of tariffs are revenue tariffs, aimed at generating government income, and protective tariffs, designed to shield domestic industries from foreign competition. The latter often arises from lobbying efforts by domestic producers who seek to maintain their market position against lower-priced imports.