Quota.....

A quota is a government-imposed trade restriction that limits the number or monetary value of goods that a country can import or export during a particular period..... 

Countries use quotas in international trade to help regulate the volume of trade between them and other countries. Countries sometimes impose them on specific products to reduce imports and increase domestic production. In theory, quotas boost domestic production by restricting foreign competition. 

How a Quota Works

Quotas are different from tariffs or customs, which place taxes on imports or exports. Governments impose both quotas and tariffs as protective measures to try to control trade between countries, but there are distinct differences between them. Quotas focus on limiting the quantities (or, in some cases, cumulative value) of a particular good that a country imports or exports for a specific period, whereas tariffs impose specific fees on those goods.

Governments design tariffs to raise the overall cost to the producer or supplier seeking to sell products within a country.

Quotas are more effective in restricting trade than tariffs, especially if domestic demand for something is not price-sensitive. Quotas may be more disruptive to international trade than tariffs. Applied selectively to various countries, they can be utilized as a coercive economic weapon.  

 

Import Quota Regulatory Agencies

The U.S. Customs and Border Protection Agency, a federal law-enforcement agency of the U.S. Department of Homeland Security, oversees the regulation of international trade, collecting customs and enforcing U.S. trade regulations. Within the United States, the three forms of quotas are absolute, tariff-rate, and tariff-preference level:

1.     An absolute quota provides a definitive restriction on the quantity of a particular good that may be imported into the United States, although this level of restriction is not always in use. 
2.   Tariff-rate quotas allow a country to import a certain quantity of a particular good at a reduced duty rate. Once the tariff-rate quota is met, all subsequently imported goods are charged at a higher rate. 
3. A separate set of negotiations create tariff-preference levels, such as those established through Free Trade Agreements (FTAs).