The EU has expanded since its post-World War II inception (and contracted, thanks to Brexit) to become a major global player.

Here are a few facts about the European Union:

- Number Two -

The EU -- a 27-nation bloc boasting a combined population of 450 million -- is the world's second-biggest economy, according to the International Monetary Fund, with a total nominal GDP of $19.3 trillion.

That puts it behind the United States (GDP $28 trillion) and ahead of China ($18.6 trillion).

Some other institutions -- the World Bank for instance -- put the EU in third place, behind China. And when you divide respective GDPs by population figures, or take exchange rate fluctuations into account, the ranking is even more open to debate.

- Who's the boss? -

The EU has three presidents heading its main institutions.

Currently they are Ursula von der Leyen of the European Commission, Charles Michel of the European Council, and Roberta Metsola of the European Parliament.

There's little question that von der Leyen has become the face best-known globally for representing the bloc.

But there is a constellation of other presidents floating around, too, for bodies such as the European Central Bank, the European Court of Justice, and the European Court of Auditors.

And, just to spice things up a bit, there is also an "EU presidency" which is filled on a rotating basis by each of the member countries for a six-month period. Ministers from the EU presidency chair many of the meetings in Brussels and influence the agenda.

- Stars and symbols -

With 27 member countries, you'd expect the EU flag to have 27 stars, right? Just like the 50 stars on the US flag representing the 50 US states?

Nope -- the EU flag has always had just 12 stars in a circle on a blue field.

That's because the design has been around since 1955 and was taken from the same flag that flies over the Council of Europe -- which, by the way, is a non-EU institution that is Europe's main human rights organisation and has 46 member states.

Officially, the EU flag represents "the identity and unity of Europe" and the starry circle is "a symbol of unity".

Less mentioned is that one of its designers, Arsene Heitz, once explained the astral circle was inspired from the starry crown seen above icons of the Christian figure of the Blessed Virgin Mary. The Council of Europe, though, maintained that was a coincidence.

Bonus bit of trivia: the EU's official anthem is Ode to Joy, by Beethoven -- also borrowed from the Council of Europe.

In practical terms, however, probably the most potent symbol of the EU is the euro -- even though the single currency is used by only 20 of the EU's 27 countries.

- What's the EU capital? -

Trick question. There isn't one -- technically.

De facto, Brussels is the bloc's capital by virtue of it hosting the European Commission, the European Council and a European Parliament complex.

Under the EU's treaties, the official seat of the European Parliament is in France on the border with Germany, in the city of Strasbourg, in a nod to post-war reconciliation.

Many EU lawmakers grumble about the near-monthly train, plane and road trips from Brussels needed to attend week-long parliamentary plenaries in Strasbourg. France is adamant the treaty wording stands.

A lot of EU business is also conducted in Luxembourg, seat of the European Court of Justice. And various EU agencies are deliberately spread across member countries.

- Making life easier... eventually -

The EU can boast a list of achievements that have made life easier for its residents and businesses within the bloc: a common currency, air and rail passenger rights, passport-free travel, mobile phone roam-like-at-home, international protection for geographically specific traditional products like Champagne, and enhanced online privacy.

But many decisions have to run the gauntlet of lengthy negotiations, between member countries and between the countries and the European Parliament.

A few key areas give each of the 27 countries the power of veto, such as on EU membership, citizenship, EU finances and aspects of common foreign and defence policies and taxation.

Other issues can be decided through a weighted majority voting of countries.

But, as the EU looks to expand in the future -- it has assessments running for 10 countries wanting to join eventually, including Ukraine and Turkey -- the problem of actually getting decisions taken is growing.

Many current member states recognise the need for a streamlined process -- but several smaller countries in particular are loath to see their voices diminished.

That, then, will be one of the important questions for the next European Parliament, European Council and European Commission to focus on.