The Chinese have at times held the yuan (the Chinese currency also called a renminbi, {pronounced "RNB" which is slang like a buck or clams for US currency}) exchange rate with the dollar constant. This fixed exchange rate has caused the United States to accuse China of undervaluing it's currency to keep exchange rates favorable for China. Undervalued currency keeps exports from China desirable to the US consumer. How and why this process works and helps China to be one of the largest exporters in the world?