A lot of what the EU does is about bringing people in Europe closer together.
It tries to make it easier for Europeans to buy and sell things to each other. This is done by changing the rules that control trade.
It is also getting rid of controls that stop people from EU countries moving around freely inside the Union.
The changes have not always been popular in the UK.
The EU backs things like exchange visits that help ordinary Europeans to understand what they all have in common.
But there are some who think that the EU does too much, mainly if it tries to create one rule for everyone in Europe and then makes people obey it even if they dislike that rule.