The document discusses the costs associated with adopting a common currency between countries. It outlines several costs such as the loss of independent monetary policy which prevents countries from moderating demand shocks and influencing inflation rates. Additional costs include labor markets being affected, divergence in wage and price developments between countries, and the costs for individuals and institutions to adjust to the new currency. Overall, adopting a common currency is difficult for diverse countries and the costs may outweigh the benefits except in currency areas like the Eurozone where countries are more economically integrated.