The UK triggered Article 50 of the Treaty on European Union (TEU) on March 29, 2017, to begin the Brexit process. Article 50 provides the legal basis for a member state to leave the EU and sets out a two-year timeframe for negotiations on the terms of withdrawal. The triggering of Article 50 marked the start of a complex and often contentious process, including negotiations on issues such as trade, citizens' rights, and the Northern Ireland border. After months of negotiations, an agreement on withdrawal was reached between the UK and the EU, which was ratified by the UK Parliament and the European Parliament in January 2020. The UK officially left the EU on January 31, 2020, but a transition period was agreed to last until December 31, 2020, during which time the UK and the EU negotiated a future relationship.