in 1993, with the "treaty of maastricht" it changed its name to the european union. now the member countries work together not only in politics and economy (coal, steel and trade), but also in money, justice (laws), and foreign affairs. with the schengen agreement, 22 member countries of the eu opened their borders to each other, so people can now travel from one country to the other without a passport or identity card. many of the countries of the eu also share a currency, which is called the euro. 10 new countries became members of the eu in 2004, 2 more became members in 2007, and 1 more in 2013. in 2016, the united kingdom voted to leave the eu. today there are 27 member countries altogether.