The European Parliament is the directly elected parliamentary institution of the EU. It exercises the legislative function of the EU, affecting the lives of the 510 million people living in the 28-member bloc.
Article 14 of the 2010 Lisbon Treaty describes the functions of the European Parliament:
"The European Parliament shall, jointly with the Council, exercise legislative and budgetary functions. It shall exercise functions of political control and consultation as laid down in the Treaties. It shall elect the President of the Commission."
LEGISLATIVE POWERS: The ordinary legislative procedure gives the same weight to the European Parliament and the Council of the European Union on a wide range of issues such as economic governance, immigration, energy, transport, the environment and consumer protection.
Most European laws are adopted jointly by the European Parliament and the Council.
Parliament may approve or reject a legislative proposal from the Council, or propose amendments to it.
The Council is not legally obliged to take account of Parliament's opinion but in line with the case-law of the Court of Justice, it must not take a decision without having received it.
BUDGETARY POWERS: Parliament and the Council of the European Union together constitute the EU's budgetary authority, which decides each year on its expenditures and revenues.
The Commission drafts the budget and sends it each April to the Council of Ministers and the Parliament.
Parliament debates and, if necessary, proposes changes. The draft is then sent back to the Council which can propose changes and send it back to Parliament for a second reading. Parliament can then adopt or reject it.
In the case of "compulsory expenditures", related to international agreements and agriculture, it is the Council that has the last word.
In the case of "non-compulsory expenditures", Parliament decides in close collaboration with the Council. These include areas such as rural development, infrastructure and research.
Parliament also monitors how the EU's executive, the European Commission, implements the budget.
Martin Schulz was president of the European Parliament until he stood down to become SPD candidate for chancellor in the 2017 German elections
OVERSIGHT POWERS: The European Parliament has major supervisory powers over the European Commission and the Presidency of the Council.
Parliament can dismiss the Commission which needs to submit regular reports, annual legislative programs and reports on the implementation of the budget.
Parliament confirms nominations put forward by the Council for positions of President of the European Commission and High Representative of the Union for Foreign Affairs and Security Policy.
The Presidency of the Council needs to report to Parliament on its priorities and progress.
Parliament also monitors the work of the Council of Ministers.
EU leaders attend a special meeting in Brussels in April 2017 to discuss Brexit negotiating guidelines
APPOINTMENTS: Parliament appoints the President of the Commission, approves the appointment of the Commission and has the power to dismiss it.
Parliament also appoints the president and vice-president of the European Central Bank which presents its annual report to Parliament in a plenary session.
Parliament appoints the European Ombudsman who investigates complaints about maladministration in the institutions and bodies of the European Union.
Parliament consults on the appointments for the Court of Auditors.
Every European citizen has the right to petition Parliament to seek remedies to specific problems.