President Donald Trump revealed his most sweeping economic measure yet Thursday, announcing reciprocal tariffs that could come as soon as this spring, which Trump argues would level the playing field in global trade—though economists project they would increase inflation this year.

Here’s what you need to know about reciprocal tariffs and who might be impacted by Trump’s plan. Reciprocal tariffs refer to tariffs—the taxes charged on imported goods—the U.S. government plans to levy against global trading partners that are equal to the existing tariffs foreign countries have set against American goods.