The European Union (EU) is an economic and political union of 28 countries. It operates an internal (or single) market which allows free movement of goods, capital, services and people between member states.
The EU countries are:
Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and the UK.
The European Economic Area (EEA)
The EEA includes EU countries and also Iceland, Liechtenstein and Norway. It allows them to be part of the EU’s single market.
Switzerland is neither an EU nor EEA member but is part of the single market - this means Swiss nationals have the same rights to live and work in the UK as other EEA nationals.
Any other country is non-EU
More details can be found here: