Tariffs are in the news at the moment. But what are they?Related video above: Trump threatens tariffs to enforce migrant deportationsHere’s what they are and what you need to know about them:Tariffs are a tax on importsTariffs are typically charged as a percentage of the price a buyer pays a foreign seller. In the United States, tariffs are collected by Customs and Border Protection agents at 328 ports of entry across the country.U.S. tariff rates vary: They are generally 2.5% on passenger cars, for instance, and 6% on golf shoes. Tariffs can be lower for countries with which the United States has trade agreements. For example, most goods can move among the United States, Mexico and Canada tariff-free because of Trump’s US-Mexico-Canada trade agreement.Mainstream economists are generally skeptical of tariffs, considering them a mostly inefficient way for governments to raise money and promote prosperity.There’s much misinformation about who actually pays …