How is the EU useful to use?

The EU allows natives from the involved countries to work in the other involved countries. The EU also manages the Euro, allowing the involved countries to work on regional issues, rather than their economy (not including the UK (The United Kingdom (England, Ireland, Scotland, Wales) which uses the British Pound). The EU also creates a mutual bond between the collection of countries part of the EU, so that if war were to break out, all those countries in the EU would be automatically in alliance.