The financial sector is well developed in Europe. Many European cities are financial centers, the largest of which is the City of London. Continental Europe's financial sector was aided by the introduction of the euro as the single currency. This made it easier for European households and firms to invest in companies and place money in banks in other European countries. In addition, the euro has acquired the position of a global "reserve" currency, which means that many countries outside the euro area have reserves of this currency as part of their foreign exchange reserves, which are mainly used for transactions in commodities. Currently, the euro is the second most common reserve currency in the world after the US dollar, and in some countries, such as Russia, the euro is the main reserve currency. http://www.immigration-residency.eu/