More than 350 million people across 28 European countries are eligible to vote and to choose their next representatives that will sit here in the European Parliament.

But with 28 countries voting on different days, each with its own electoral laws and procedures, it's bound to get complicated.

The first European parliamentary elections took place back in 1979, when only 9 countries were members of what was then called the European Economic Community.

Since then, that community has expanded into what's now known as the European Union.

And voters head to the polls every five years to elect the 751 members of the European parliament or MEPs.

The number of MEPs assigned to each country varies and corresponds to the country's population.

For example, the EU's most populous country, Germany, elects 96 lawmakers, while Luxembourg only gets 6 seats.

In some countries like Italy, MEPs represent a specific region.

In others like France, they represent the entire country.

So now let's get into how all of these MEPs are actually elected.

Voting is open to all EU citizens, and in Belgium, Bulgaria, Cyprus, Greece and Luxembourg, it's actually compulsory.

This time around, the elections are spread over four voting days, between May 23rd and 26th.

Here in Belgium, citizens cast their vote on Sunday, whereas the British and the Dutch have their say on the previous Thursday.

The results, however, are kept secret until every country has voted.

Next, let's talk about the method, or should I say methods, that the EU uses to elect its representatives.

Stay with me—this is where it gets a little bit tricky.

Depending on where a voter is based, they could be using one of three systems.

The closed list, open list or single transferable vote system.

What they all have in common is that they aim to achieve proportional representation.

That means the number of votes a party gets, will directly correspond to the number of seats they receive in the European parliament.

In the closed list system, citizens vote for parties.

Those parties have already selected a fixed list of candidates.

So if a party gets 20% of votes in a country allocated 10 MEPs;

The two top people on the party's list will become Members of the European Parliament.

In the open list system, Europeans vote for a party, but can also indicate their favorite candidate.

This means voters can actually change the order of the party's list.

Therefore influencing which of the party's candidates become MEPs.

In the single transferable vote system, voters can choose as many candidates as they like and then number them by preference.

These votes are counted in phases.

First, people's number one preferences are counted.

Any candidate who passes a certain quota of votes is elected.

Any votes exceeding that quota are then changed into the ballot's second preference.

And transferred to the other candidates.

If there still aren't enough votes to reach the quota, the candidate with the lowest amount of votes is eliminated.

And those votes are transferred to the second preference too.

This process is repeated until all seats up for election are filled.

One more thing.

Some countries have what's called an electoral threshold.

Which means that a party or a candidate needs to get a certain percentage of the national vote in order to get a seat here in Brussels.

This, in theory, keeps fringe or extremist parties from winning seats without meeting a minimum level of widespread support.

So citizens select their parties and candidates at a national level.

They then align themselves with other EU politicians with similar views and form one big pan-EU group at the European Parliament.

These alliances help stand-alone parties and independent politicians gain more influence.

The big elephant in the room is of course Brexit.

The European Parliament's 751 seats will shrink down to 705 once the U.K. leaves the European Union.

The plan is to reallocate some of those seats to under-represented countries like France, Spain, Italy and the Netherlands.

There was another proposal on the table too—transnational lists.

It would have transformed U.K. seats into seats for a pan-European constituency.

Its advocates, who include the likes of French President Emmanuel Macron, say it would strengthen the European democracy

by forcing parties to discuss European, not just national, issues.

EU lawmakers have rejected this idea but it does bring us back to why this year's European elections are seen as so important.

Pro-Europe parties have dominated the Parliament, but nationalists and eurosceptics are gaining traction.

Whoever sits in the European Parliament will help determine what happens next in this economic and political union.