Britain voted in June to exit the European Union, the first country to ever leave the bloc.

E.U. member states Non-E.U. countries Squares are sized according to the population of each country. Iceland Sweden Norway Estonia Finland Ireland Latvia Britain Lithuania Netherlands Belarus Denmark Poland Ukraine Belgium Germany Czech Rep. Luxembourg Slov. Moldova Romania Austria France Hungary Bulgaria Slovenia Liechtenstein Serbia Switzerland Croatia Turkey Bosnia and Herz. Spain Portugal Montenegro Albania Macedonia Italy Cyprus Greece Malta Norway Britain Neth. Poland Belgium Ukraine Germany Rom. France Austria Spain Turkey Italy Greece The New York Times

The European Union is a club binding 28 countries by treaty but split by how much the members really want to do together.

Take the example of Britain, long one of the more demanding members.

Britain’s main goal has been opening up the economies of other members to freer trade. Successive governments in London have pushed to liberalize sectors like financial services and energy.

But Britain is reluctant about many other aspects of the bloc’s stated goals. Rather than opening its borders, it has kept checks in place and does not have to jettison the pound for European notes and coins.

Schengen countries Iceland Norway Britain Poland Germany Rom. Bulgaria France Switz. Croatia Turkey Spain Italy Cyprus Allows free movement across the participating countries. Some non-European Union countries, like Norway and Switzerland, participate, and some European Union countries, like Britain, do not. Eurozone countries Britain Sweden Denmark Poland Germany Cz.Rep. Rom. Hungary Bulgaria France Croatia Spain Italy Where the euro is the country’s currency.

Britain, like Ireland, can also opt out of cooperating with other member states in the areas of policing and justice. Denmark does not even have that option after voting in a referendum in 1992 to curtail participation in the fields of justice and home affairs.

Then take the example of Germany, a founding member of the bloc as a signatory of the Treaty of Rome in 1957.

Germany frequently shares the economic goals of Britain. Yet Germany is the strongest backer of the euro, the European currency overseen by the European Central Bank in Frankfurt used in 18 other countries.

Germany also allows free movement of people across its borders from the so-called Schengen area, which is made up of 26 countries.

While the single currency is confined to the European Union, the Schengen area has wider reach. It includes Iceland, Liechtenstein, Norway and Switzerland — countries that are not even members.

European Economic Area countries Iceland Norway Britain Poland Germany France Spain Italy Provides for the free movement of labor and capital. NATO countries Norway Iceland Finland Britain Sweden Poland Germany France Austria Turkey Spain Albania Italy Cyprus Malta A military alliance that provides a collective defense for its members.

That makes the Schengen area somewhat similar to the European Economic Area. The European Economic Area permits free trade and promotes other forms of cooperation in all 28 members of the European Union, Iceland, Liechtenstein and Norway — but does not include Switzerland.