The European Union (EU) consists of 28 states with a combined population of more than 500 million citizens.
It can be considered to be a government with its own laws, currency and vision.
The organisation was formed in 1957 by France and Germany, which vowed to form a union in order to bring about peace between the countries of Europe.
But with the current migration and economic crises, does the EU still benefit its member states?
Here are the main factors to consider:
The Euro is the second most used trade currency after the dollar in the world and has been adopted by 18 of the 28 EU member states.
This eliminates exchange rate tariffs, allows easier price comparisons and low interest rates, and has reduced the cost of trading bonds and equity.
On the other hand, should a country be in a financial crisis, it won't be able to devalue its currency.
Neither can interest rates be determined by the country’s economic business cycle.
This can leave countries at an economic disadvantage.
Mobile labour force
The EU promotes the free movement of workers between countries.
If you're an EU citizen, you're allowed to work and reside in another EU country.
Working conditions, as well as social benefits and tax advantages are equal to the citizens of that country.
A study conducted in 2013 by the EU suggests that only 3% (8 million) of the total mobile labour force migrates between countries.
Over a million migrants and refugees entered Europe in 2015, almost four times the number in 2014.
The hardest hit countries include Greece, Italy and Hungary.
The EU's visa-free Schengen Zone, which eliminates border checks, has been under strain after some EU countries implemented temporary border restrictions.
Member countries of the EU are allowed to trade freely within common regulatory frameworks.
The trade policies are designed to reduce trade costs and allow for more open markets.
This increases competitiveness amongst countries and prevents the importing of illegal goods through the back door.
There has been a 70% increase in trade between free-trade countries in the EU from 2002 to 2013.
Countries thinking of leaving the EU
The UK will vote on June 22 on whether to remain in the EU or leave.
However, the Brits are not the only nation who want a chance to vote.
Should the EU cease to exist, the sending of money between countries would become more expensive, trade may suffer and workers will have to return to their countries of origin.
The EU has brought a sense of unity in Europe with a boom in trade and investor confidence, which could come under threat.
Should a country intend to withdraw, it will likely hold a referendum first.