What is a tariff and how does it work?

Tariffs have dominated headlines since President Donald Trump took office just over two weeks ago, as he threatened steep, sweeping tariffs on goods the United States imports from its three largest trading partners — Mexico, China and Canada — on Tuesday.

​ Tariffs have dominated headlines since President Donald Trump took office just over two weeks ago, as he threatened steep, sweeping tariffs on goods the United States imports from its three largest trading partners — Mexico, China and Canada — on Tuesday. Read More Breaking News, Latest News and Videos | CNN