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 if the Lisbon Treaty comes into force.
Europe's political alliances are shifting as newly-elected Euro MPs decide where they will sit in the Strasbourg parliament.
National issues dominated the June elections, so the political blocs in the European Parliament are set to be broad churches, as they were before. The Greens were unusual in having a strongly pan-European platform.
The European Parliament will hold its first full session in Strasbourg on 14-16 July.
Now there are 736 MEPs, compared with 785 in the 2004-2009 parliament.
The election produced a clear victory for centre-right parties. The 25 British Conservative MEPs have left the centre-right European People's Party (EPP), but the EPP remains the strongest bloc.
NEW PARLIAMENT IN FIGURES
Half of MEPs were re-elected, half are new
Highest proportion of newly-elected MEPs is from Lithuania
Youngest MEP - Emilie Turunen (Danish), 25
Oldest MEP - Ciriaco De Mita (Italian), 81
Women MEPs - 35.3% (31.2% in old parliament)
Finland has most women MEPs (61.5%)
Malta has no women MEPs
The EPP has gained some Italian politicians who previously sat with the conservative UEN bloc.
The UEN has now disintegrated, with Ireland's centrist Fianna Fail party abandoning it in favour of the liberal group, ALDE.
The British Conservatives have formed an anti-federalist bloc called the European Conservatives and Reformists Group, with 15 MEPs from Poland's Law and Justice Party (PiS), nine from the Czech Civic Democratic Party (ODS) and a handful from other countries.
Meanwhile, the Party of European Socialists (PES) has been transformed into the Progressive Alliance of Socialists and Democrats in Europe (S&D), taking in some MEPs from the Italian Democratic Party who previously sat with the liberal bloc.
Thirty-two right-wing Eurosceptic MEPs have formed a group called Europe of Freedom and Democracy, led by the UK Independence Party (UKIP). This means the Independence and Democracy group (IND/DEM) no longer exists.
It is not yet clear whether ultra-nationalists will also form a new bloc or remain independent. Membership of a bloc gives MEPs extra influence, as formal groups benefit from administrative back-up, funding and more speaking time.
The minimum requirement to form a group is 25 MEPs representing at least seven countries.
Parties new to Strasbourg include the far-right British National Party, the anti-immigration Freedom Party (PVV) from the Netherlands and the Swedish Pirate Party, which campaigns for freedom on the internet.
One of the parliament's first tasks will be to elect a new parliament president and vice-presidents. The post of president is likely to be divided, with a member of the EPP and one from either S&D or ALDE each serving for two-and-a-half years.
It is not yet clear whether the parliament will vote at this session on the candidacy of Portuguese conservative Jose Manuel Barroso, who hopes for a second term as European Commission president. The vote might be postponed until the autumn, depending on the strength of opposition to him.