An economic union is an agreement between two or more nations to allow goods, services, money and workers to move over borders freely. The countries may also coordinate social and financial policies to support this common market.
The European Union (EU) is an example of an economic union. The countries of the EU coordinate their respective economic policies, laws and regulations so they can work together to address economic and financial issues. The EU also has a common currency, the Euro, used by 19 EU members.
An economic union is different from a customs union. The members of a customs union enjoy free movement of goods but do not typically share currency or allow workers to move freely across borders.