What are trade tariffs and who will they affect?

As the US and China plunge into a tit-for-tat trade battle, we look at what's at stake

• China retaliates with tariffs after US begins trade war

Tariffs are border taxes charged on foreign imports. Importers pay the applicable charges at the point of entry to the customs agency of the country or economic bloc imposing them.

Related: China denies it will be first to impose tariffs on $34bn of US goods