"Brexit" refers to the United Kingdom's (UK) decision to leave the European Union (EU), which was officially initiated after a referendum held on June 23, 2016. In this referendum, approximately 52% of voters chose to leave the EU, while 48% voted to remain. The decision was driven by various factors, including concerns over immigration, sovereignty, and economic policies. The UK formally exited the EU on January 31, 2020, entering a transition period that lasted until December 31, 2020. During this time, the UK and the EU negotiated their future relationship, covering trade, security, and other areas of cooperation. The final agreement, known as the Trade and Cooperation Agreement, took effect on January 1, 2021.