The EU is a conglomerate of European nations. These nations have trade deals and partnerships with one another. Having membership in the EU allows you to travel between EU nations without a passport and these countries all share a currency called the Euro. The EU is a beginning step towards globalization in which nation states will eventually dissolve and there will be one singular government entity. The UK has voted to leave the EU because of many reasons. They were getting bad trade deals, massive amounts of immigration into the country were making competition for jobs fierce and the overall job market and economy were not in the best shape. Many people were having a hard time and many people were living in poverty. The UK has pretty much just given a huge middle finger to the EU and the elite class pushing globalization on its people. This could have extreme effects on the EU. It might cause it to collapse eventually if more nation states decide to leave. If that happens, new trade deals will have to be drawn up between the nations and it might cause a lot of unrest between nations if they cannot come to terms on new trade deals that are fair for all nations involved. There are a lot of far right/nationalistic movements going on in Europe right now which is conscerning because nationalism in Germany and many European countries was one of the main contributing factors to WW1 and WW2. Should be interesting to see what comes from this. I hope the situation can be solved peacefully in coming years.