On the surface
The European Union (EU) is an international organization seeking to unify Europe both financially and socially by promoting unity among European countries. While countries of all sizes make up the EU, the most prominent of those countries are France, Britain, and Sweden. But Britain has put on the appearance of backing out of the EU–commiting a “Brexit”, or a British exit.
And as one of the biggest countries in the EU, Britain’s exit could potentially impact not only the EU, but itself as well.
The EU accounts for 50% of Britain’s imports and exports–about 15% of Britain’s total GDP. By leaving the EU, Britain could find itself in an economic downturn.
The EU itself could also see negative effects. Italy, for example, is just one of the EU countries that has been re-evaluating its position in the EU; the Brexit could be the tipping point that causes the secessions of multiple countries.
The EU is only able to work through the combined efforts of many European countries. If Britain were to secede, it could set off a domino effect–toppling the EU.