How do tariffs restrict trade and protect domestic industries?

The cost of tariffs to the economy is not trivial. the World Bank estimates that if all barriers to trade such as tariffs were eliminated, the global economy would expand by 830 billion dollars by 2015.

Tariffs are essentially taxes or duties placed on an imported good or service by a domestic government, making domestic goods cheaper for domestic consumers and imported goods more expensive for companies exporting goods from their industry into the domestic industry.