What Actually Impedes the Pound Entering into the Euro?

As one of the dominant members in European Union (EU), the United Kingdom is different from most EU members. Instead of using euro, the single currency used by almost every EU member, the United Kingdom still keeps using its own currency: pound. It seems that it is due to some political reasons for the UK to separate from the euro zone. However, when observers look inside deeper they found all the reasons are related to the economy. This paper will use relative Purchasing Power Parity (PPP) to compare the national competitiveness among the UK and main euro land countries. Some other economic indexes, such as annual GDP growth rate, unemployment rate and interest rate, will be compared successively as well. In the end, this paper will give a comprehensive conclusion on the real reasons for the pound being outside euro zone.