There's a big argument going on about this. It is mostly between these two groups of people.

Anti-Europeans (Eurosceptics)

These are people who think that getting more closely involved with Europe is a bad idea.

Some Eurosceptics feel that the UK is different from other European countries.

They are often worried that the UK is losing its independence and identity.

Pro-Europeans

They think being in the EU is a good idea and often want the UK to start using the Euro currency.

Pro-Europe people think Britain will benefit from being part of a larger group of countries.