The European parliament is the only directly elected EU body. It represents the people of the EU in contrast to the Council of Ministers, which represents the governments.
Elections have been held every five years since 1979 - before that members were drawn from national parliaments.
The European parliament's powers have steadily increased with each change of the EU treaties. Most new laws in member states now stem from the need to implement European legislation - and most of that is amended and adopted by the European Parliament.
Use this guide to find out more about it.