The first thing to clarify is that the EU is not as big as you might have been led to believe — the European Commission employs fewer people than Edinburgh and Glasgow City Councils, but serves 500 million people rather than 1 million. There are 751 MEPs, but that is 65 fewer than there are members of the House of Lords, just one chamber of one member state Parliament (and MEPs are democratically elected). Yes, there is a lot going on in Brussels, but it is not that complicated.
Central to explaining how the various institutions work is understanding that the EU is not - in structure or intent - a federal country like the USA. At its heart are a collection of sovereign member states who came together to form a single market.
A single market needs rules to function and defining what things are means that trade can be conducted fairly and without discriminating against any individual citizen. Likewise, for Scots and other EU citizens to take up their rights to travel, study, live, work or retire in any other member state, we need to do that on the basis of laws.
If there is not agreement between the MEPs and the other EU institutions, the law doesn’t happen. This will also be true for the Article 50 negotiations. The withdrawal agreement will require the approval of both a qualified majority of the Council and a majority of MEPs.
There are four main parts to the EU:
Did you know?
With the exception of the European Court of Justice, each of these institutions has a President which means there are three presidents of Europe.