What major event occurred in June 2016 related to Brexit?

In June 2016, the United Kingdom held a referendum in which the population voted on whether to remain in or leave the European Union (EU). The outcome of this referendum was that a majority of voters chose to leave the EU, marking a significant political and economic decision known as Brexit. This event has had substantial implications for the UK's political landscape, international relations, and economic policies moving forward.

The other options do not accurately describe the referendum's outcome or its significance. The UK did not vote to remain in the EU; rather, the vote overwhelmingly favored leaving. The EU did not expand to include more countries in that context; instead, discussions about the EU's future began after the decision to leave. Lastly, while general elections are an important part of the UK's democratic process, this particular event in June 2016 was specifically focused on the issue of EU membership, separate from any general election activities.