Guide to the European Parliament

EPP - European People's Party (Christian Democrats)

S&D - Progressive Alliance of Socialists and Democrats in Europe (centre-left)

ALDE - Alliance of Liberals and Democrats for Europe (liberal)

GUE/NGL - European United Left-Nordic Green Left (left-wing)

Greens/EFA - Greens/European Free Alliance (Greens and regionalists/nationalists)

ECR - European Conservatives and Reformists Group (right-wing)

EFD - Europe of Freedom and Democracy (Eurosceptic)

NA - Non-attached (MEPs not part of any group)

The number of MEPs will increase to 754 under the Lisbon Treaty.

Most MEPs belong to one of the parliament's political groups. None has an overall majority, so amendments need the support of more than one group to get through. On most issues the parliament divides along classic left-right lines.

There are now 736 MEPs - down from the 785 in the outgoing parliament, which grew after Bulgaria and Romania joined the EU in 2007.

Soon the number of MEPs will increase temporarily to 754, since the Lisbon Treaty has been fully ratified. But from 2014 the number will be 751, the final figure set by the treaty.

For a group to be recognised, it needs at least 25 MEPs from seven different countries.

The larger the group, the more funding it receives, the more key committee posts it gets and the longer it can speak in debates.

Some groups remain broad churches after the 2009 European election. The new Socialist group has expanded to include some Italian MEPs who used to sit with the liberals.

But the British Conservatives have left the EPP-ED, regarding it as too enthusiastic about EU integration. The Conservatives are leading the new European Conservatives and Reformists Group, which includes right-wing MEPs from the Czech Republic and Poland.

Euro MPs build new alliances