Latvia takes over the six-month rotating presidency of the Council of the EU.
Lithuania adopts the euro as its currency, becoming the 19th member of the euro area.
The European Commission launches the European Year of Development, which will focus on raising awareness of development across Europe.
Mons (Belgium) and Plzeň (Czech Republic) are the European Capitals of Culture 2015. Both cities will host events to promote their local culture.
A terrorist attack on the satirical magazine 'Charlie Hebdo' in Paris leads to demonstrations all over Europe in support of freedom of expression, as well as new initiatives at European level to fight terrorism.
EU leaders meet at an informal European Council in Brussels to discuss three challenges facing Europe: restoring peace in Ukraine, fighting terrorism and improving the European Monetary Union, particularly in the light of the change of government in Greece, whose new Prime Minister, Alexis Tsipras, asks for a review of its situation.
The European Commission sets out its strategy to achieve a resilient Energy Union with a forward-looking climate change policy.
The European Commission presents a package of tax transparency measures as part of its agenda to tackle corporate tax avoidance and harmful competition in the EU.
Meeting in the European Council, EU leaders agree to create an Energy Union. They underline their commitment to providing affordable, secure and sustainable energy within the EU.
At a special meeting of the European Council in Brussels, EU leaders agree on four priority areas for action in response to the 1 800 lives lost in the Mediterranean when migrants attempt the perilous journey to European shores in boats. These include measures to fight traffickers, a new return programme for irregular migrants, more protection for refugees from conflict areas, and tripled resources for the the EU's search and rescue operations in the Central Mediterranean.
The European Commission unveils detailed plans to create a Digital Single Market, laying the groundwork for Europe’s digital future.
The Conservative party wins a majority in the United Kingdom general election. The party confirms that an 'in-out' referendum on membership of the European Union will be held before the end of 2017.
As part of the 'European Semester', the Commission adopts recommendations for each of the 28 EU countries, offering guidance on 2015-2016 national budgets and economic policies.
At a summit in Riga, EU leaders meet with the representatives of the six countries of the Eastern Partnership (Armenia, Azerbaijan, Belarus, Georgia, Moldova, and Ukraine). They set out a positive agenda for the future, including the need to establish strengthened and more transparent institutions, free from corruption.
Germany hosts the meeting of the G7 heads of state and government, the forum of the world's leading advanced economies. Discussions focus on the global economy and climate change as well as on key foreign, security and development issues.
Five EU Presidents reveal ambitious plans on how to deepen the Economic and Monetary Union between 2015 and 2025. The report is prepared by European Commission President Jean-Claude Juncker, together with the President of the Euro Summit, Donald Tusk, the President of the Eurogroup, Jeroen Dijsselbloem, the President of the European Central Bank, Mario Draghi, and the President of the European Parliament, Martin Schulz.
Meeting in the European Council, EU leaders discuss the situation in Greece, migration, the future referendum in the UK, security and defence, and economic issues. Furthermore, numerous other negotiations are held in Europe during the month of June to tackle the question of Greece's public debt.
The European Parliament and the Council reach an agreement to end all mobile phone roaming fees within the EU by 2017.
Luxembourg takes over the six-month rotating presidency of the Council of the EU.
Greece holds a referendum on the conditions of a support programme proposed jointly by the European Commission, the International Monetary Fund and the European Central bank. 61 % vote against the proposal and 39 % vote in favour.
At a summit in Brussels, euro area leaders and the Greek government agree on a new support programme for Greece under the European Stability Mechanism, subject to strict conditions and accompanied by support for growth and employment in the order of €35 billion.
An agreement on Iran's nuclear programme is reached between Iran and leading world powers, including the EU, represented by the High Representative for Foreign Affairs and Security Policy Federica Mogherini. The deal will ensure that Iran's nuclear programme will only be used for civilian purposes and that longstanding economic sanctions against Iran will be lifted.
The EU and Vietnam reach an agreement in principle for a free trade agreement (FTA), after two and a half years of intense negotiations.
The European Commission approves 23 funding programmes under the Asylum, Migration and Integration Fund (AMIF) and the Internal Security Fund (ISF). The total funding is approximately €2.4 billion and will help EU countries such as Greece and Italy deal with high migratory flows.
The European Commission signs a Memorandum of Understanding with Greece for a stability support programme. The European Stability Mechanism will be able to disburse up to €86 billion in loans over the next three years.
In his State of the Union speech, European Commission President Jean-Claude Juncker outlines his political vision for the future of the EU, focusing on the major challenges posed by the refugee crisis, the future of the euro and foreign policy.
EU home affairs ministers decide to relocate 120 000 asylum seekers. These people have fled mainly to Italy and Greece, large numbers of them from the war in Syria, and are clearly in need of international protection. They will be housed in other EU countries. This is a temporary measure taken to deal with the large numbers of asylum seekers making their way from Greece to other EU countries and finding some borders closed. The Commission proposes to set up a permanent relocation system as well as a further package of other measures to manage this crisis.
An informal EU summit takes a number of decisions on refugees, including the granting of additional funding of €1 billion to the UN's work to help refugees.
At a European Council meeting in Brussels, EU leaders discuss the migration and refugee crisis.
The European Commission sets out concrete steps towards completing Economic and Monetary Union. It proposes reforming the way economic policy is coordinated within the 'European Semester' and to set up 'National Competitiveness Boards' in each country.
Leaders representing Albania, Austria, Bulgaria, Croatia, the former Yugoslav Republic of Macedonia, Germany, Greece, Hungary, Romania, Serbia and Slovenia meet in Brussels and agree to improve cooperation and step up consultation between countries situated along the migration route. They decide on pragmatic operational measures that can be implemented to tackle the refugee crisis in the region.
The European Parliament gives final approval to rules banning roaming charges for using mobile phones abroad in the EU. The new rules will come into effect in June 2017.
The European Commission presents a package of initiatives to further strengthen the Single Market. Among others, these initiatives include promoting the new so-called 'collaborative economy', helping start-ups to grow and ensuring that it will be easier to offer services across borders in the future.
At a summit on migration in Valetta, European and African heads of state and government agree on an action plan designed to strengthen cooperation and address the current challenges, whilst recognising the benefits of well-managed migration and mobility between and within continents.
Terrorists launch multiple attacks in Paris, leaving 130 people dead. In a joint statement, EU leaders and heads of state and government roundly condemn these acts, calling it "an attack against us all". They pledge to "face this threat together with all necessary means and ruthless determination."
The Commission publishes its Annual Growth Survey for 2016. This kick-starts the annual ‘European Semester’ for economic policy coordination, which ensures that EU countries align their budgetary and economic plans for growth. To strengthen recovery and foster convergence, the Commission recommends building on the three main pillars identified last year for the EU's economic and social policy, i.e. re-launching investment, pursuing structural reforms and responsible fiscal policies.
EU heads of state and government hold a summit with Turkey. A joint action plan is adopted to help tackle the refugee crisis created by the situation in Syria. The EU and its Member States agree to increase their cooperation with Turkey and to step up their political and financial engagement substantially.
The European Commission adopts its new 'Aviation Strategy for Europe' to boost Europe's economy, strengthen its industrial base and contribute to the EU global leadership. By offering more connections to the rest of the world at lower prices, this strategy will benefit businesses and citizens alike.
At a UN conference in Paris, 195 countries conclude a new agreement on climate change, with the EU playing a pivotal role. It comprises an action plan to limit global warming 'well below' 2°C compared to pre-industrial levels.
At a Council meeting in Brussels, European leaders discuss migration issues, the fight against terrorism and the United Kingdom's reform demands.