The European Parliament is elected every five years, with the elections this year held over four days from June 6-9. 720 seats are up for grabs.
Parliament with blocking (and amending) power
Compared to a national parliament, the European Parliament's powers are fairly limited. It cannot propose new EU laws - only the unelected European Commission can do that.
But the parliament can block most draft legislation. It also has the power to reject EU member states' nominees for the key position of commission president and the other 26 commissioners.
The parliament has never rejected a nominee for commission president - though it came very close to turning down incumbent Ursula von der Leyen in 2019 - but it has rejected would-be commissioners.
Parliamentarians can also usually propose amendments to draft legislation, but these have to be agreed with EU member states' national governments before they can become law.
The member states are represented by their ministers in a separate institution called the Council of the European Union.
Negotiators for the two chambers typically resolve disagreements on amendments to new laws in often gruelling talks, which can run overnight.
The parliament can reject the outcome of these talks and send their negotiators back to the table.
How members are elected
Parliamentary seats are distributed among EU countries according to population: big countries get more seats than small ones.
In the current elections, there are 96 seats available in the EU's largest country, Germany, and six in the smallest, Malta.
Some countries - such as Ireland and Belgium - divide their seats among separate electoral districts, but most don't.
All countries some version of proportional representation, which aims to ensure the seats available in a given country or district are won with a roughly equal share of the vote.
For example, if a country has 20 seats, a party that gets 50% of the vote might win 10. Similarly, an individual candidate can be elected with 5% of the vote.
But the details vary, and the formulas used to allocate seats to winners can be quite complicated.
Some countries, such as Germany, use a "closed list" system that forces voters to choose between entire political parties, rather than individual candidates. Parties then distribute the seats they've won across their list of candidates.
Others use variations of an "open list" system, where voters can influence the ranking of individual candidates on the party lists. Other countries don't use party lists at all.
The political "parties" you've voted for, but never heard of
When they get to the European Parliament, political parties usually band together into different pan-European groups that most voters will be unfamiliar with.
The centre-right European People's Party (EPP) has been the largest such group for the last 25 years, though no group has ever had a parliamentary majority. The EPP includes Germany's Christian Democrats, Italy's Forza Italia and Poland's Civic Platform.
The other current blocs are the centre-left Socialists & Democrats, the liberal-centrist Renew; the Greens; the mildly eurosceptic European Conservatives and Reformists; the more nationalistic Identity & Democracy - which recently kicked out the German far-right Alternative for Germany (AfD); and The Left, a coalition of radical socialists and communists. There are also non-aligned parties and independents.
European political groups are fairly loose coalitions.
Just because two parties are in the same EU group doesn't necessarily mean they're much alike, or that they'd be on the same side if they had to share a country.
Their fringes can also overlap: a few parties in the EPP are arguably to the left of some members of Renew, for example.
On the other hand, these groups often vote as single blocs in the European Parliament.
For the ordinary voter, that raises an interesting question: Is the party you'd vote for in a national election necessarily the one you want to send to the European Parliament?