Protectionism: the conomic policy of restraining trade through tariffs, quotas o other regulations that burden foreign producers but not domestic producers.
Tariff: a tax on imports.
Quota: restriction on the quantity of goods that can be imported.
A tariff has two effects that influence (reduce) welfare:
Domestic consumption falls: lost gains from trade.
Domestic production increases: wasted resources from higher-cost production.
The revenue doesn't affect the net welfare, as it goes to the government.
Tariffs increase prices to consumers so domestic consumption falls, which creates a deadweight loss
Tariffs divert production from low-cost (world) producers to high-cost (domestic) producers and this wastes resources.
Distribution of losses and gains:
Bad for consumers
Good for domestic producers
Bad overall