Explained: What is the European Parliament?

The parliament has used this political legitimacy to claim more and more legislative power over the years, sometimes irking member states that have to negotiate rules with parliamentarians.

Yet paradoxically, despite gaining influence, the parliament has at the same time been losing the interest and votes of EU citizens - of whom only 42.6 percent participated in the last European election in 2014.

Who are its members?

The parliament consists of 751 MEPs from the 28 member states.

After Brexit and the departure of the UK's MEPs, the parliament will number 705 members.

The number of MEPs elected from an EU country depends on the size of the population, with the largest (Germany) having 96 members, down to Cyprus, Estonia, Luxembourg and Malta sending six members each.

They are elected for five-year terms. MEPs form political groups that can secure financial funding, important seats in committees, and their members can be tasked with overseeing and guiding legislative files.

Currently, the largest political group is the centre-right European People's Party (EPP) with 217 members. Centre-left socialists sit in the Socialists & Democrats (S&D) group, the second largest, while right-wing conservatives, liberals, greens, the far-left and far-right parties also have their own smaller groups to represent them.

MEPs earn almost €8,800 per month before taxes (that is EU taxes, with favourable rates compared to national ones), and in addition get generous funding for expenses and office costs.

Where is it really?

It has been the focus of ongoing controversy and has fed eurosceptic arguments against the EU's 'bureaucracy' for decades that the parliament divides itself between Brussels and Strasbourg.

Each month, thousands of parliament staff and a massive amount of paperwork travels from the Belgian capital to the French city for the plenary sessions, with special trains commissioned from Brussels.

Dubbed the 'travelling circus', the moves are said to cost EU taxpayers over €100m each year.

In 2013, MEPs themselves voted to back a single seat for the parliament, but - sadly and perhaps peculiarly - it is not up to them to decide.

In 1992 EU governments agreed to lay down in a treaty that the parliament's official seat is in Strasbourg, and since France is not willing to give that up, the circus will keep on rolling.

What is it doing?

The parliament has the right to adopt and amend legislation in tandem with member states and also participates in negotiating the EU budget. The vast majority of EU legislation happens in the so-called "ordinary legislative procedure".

Under this procedure, the commission makes a proposal, the parliament appoints an MEP responsible for the file, and negotiations start with the member states, once both parliament and the member states represented in the council of the EU agree their own initial position.

Negotiations on legislation are done in the secretive, informal "trilogue" meetings with representatives from the commission, the council and parliament sitting together hammering out compromises. There were 251 such trilogues in 2017.

Once a consensus is reached, the legislation is then adopted by the council and voted in the parliament's relevant committee and, later, the plenary.

The parliament is also responsible for electing the president of the European commission.

After a European election, EU governments haggle over possible candidates "taking into account" the result of the elections, as the Lisbon Treaty stipulates.

Since 2014, the parliament, under the so-called 'Spitzenkandidat' process, has attempted to force governments' hands by pushing them to elect the candidate that manages to secure a majority in the parliament.

Candidates for the different commission portfolios also have to go through a parliamentary grilling.

Who are the power-brokers?

Some of the most powerful posts in the parliament are quite visible: the president represents the EP in meetings with EU leaders, and participates in key decisions.

The leaders of the political groups are key in deciding what gets on the parliament's agenda, who will be members of the committees, deciding on institutional issues, how politically-sensitive topics will be handled, and which party gets to steer important legislative files.

The fortnightly Thursday meetings of the "conference of presidents" is the governing body of the parliament. It consists of the president and the political group leaders.

A less visible, but no less powerful, hub is the "bureau", which deals with issues relating to the budget, administration, organisation and staff of the EP.

It is composed of the president, the 14 vice-presidents of the parliament and the five quaestors, responsible for administrative and financial matters.

Behind both of these bodies stands the all-powerful secretary-general of the parliament - a post that has been held by the German Klaus Welle since 2009. He is responsible for what gets onto the table of the president, the conference of presidents and the bureau.

Rapporteurs are MEPs responsible for specific reports on legislative files.

They are also key actors as they set the tone for the parliament's position on a specific initiative or issue, and work together with shadow rapporteurs from other political groups in their committee to prepare a common position and then lead negotiations with member states.

The election of rapporteurs is done through a complicated points system, in which political party groups bid for a report or a topic, like in an auction. In other cases, groups themselves agree on an appointment.

Is it a Tower of Babel?

Almost 8,000 people work in the parliament, either in the administration or attached to political parties and their politicians. Some of them are based in Luxembourg.

Altogether, they speak the 24 official languages of the EU - and Brexit will not change that, as English will remain one of the official languages.

To guarantee the same working conditions for everyone, all documents and debates are available in all the languages.

There are 552 possible language combinations, and around 300 staff interpreters and more than 1,500 external accredited interpreters to make sense of it all.

For the plenary session weeks, some 700 to 900 interpreters are on hand. The parliament also employs about 700 translators, who monthly translate more than 100,000 pages of documents.