DOVER, UNITED KINGDOM - MARCH 7: An aerial view of the white cliffs of Dover on March 7, 2016 in Dover, England.The United Kingdom, a member of the European Union (EU), an economic and political partnership involving 28 European countries which allows members to trade together in a single market, will on June 23 hold a referendum to decide whether or not to remain part of the EU. (Photo by Ben Pruchnie/Getty Images)
