It's a new year and a new chapter for the UK's relationship with Europe. How millions of people live, work and travel will look very different in 2021.
That's because the transition period - when the UK continued to follow the EU's rules - ended on 31 December. Now a post-Brexit trade deal, reached just before the deadline, has come into force.
So, with this historic change looming, the BBC spoke to Europeans in the UK, and British people in Europe, about what Brexit could mean for them.
Catalina-Anca Toader from Onesti, Romania... now living in London
I came to the UK more than five years ago when I was accepted by the University of Westminster. I graduated with a first-class degree in 2018, and now work for a digital advertising agency in London.
I hold settled status and plan to apply for UK citizenship in 2021.
During the Brexit negotiations, I was concerned about the exchange rates as well as potential longer queues at airports. But I was mainly worried about whether the UK would impose stricter rules for citizenship and if my student loan repayments would be affected.
I was ultimately left counting down the days until the end of the transition period, worrying that the UK and the EU wouldn't reach an agreement.
So I'm happy with the deal at this stage and, hopefully, I'll soon be able to have dual citizenship. But I do think people may need more time to prepare for the sudden changes.
Jason Carter from the UK's Isle of Wight... now living in Stockholm, Sweden
I first arrived in Sweden as a student in 1999. I met my wife, Jessica, in Stockholm around that time but only moved here permanently in 2006. I live here with Jessica and our 11-year-old son, Ulf.
I became a Swedish citizen in 2016 and have dual citizenship. I applied in April ahead of the Brexit vote because I wanted to ensure I remained an EU citizen afterwards.
As someone whose life has been altered by the opportunities and rights that being a member of the EU gave, I was concerned what would happen to those rights. In particular, the right for my family to resettle in the UK one day.
When I married Jessica we both had the right to live and work in the UK or Sweden. Any attempt to return to the UK would likely be extremely difficult now - so the future we had planned is now no longer easily available.
I had also hoped that my son would one day be able to spend time on the Isle Of Wight, working summer jobs and living in the UK. But this is not as easy as it once would have been.
I don't think this is the deal that anyone wanted. But the fact a no-deal Brexit was averted at the 11th hour is perhaps more of a cause for celebration.
A Brexit deal was agreed, days before a deadline. It means that the UK and the EU can continue to trade without extra taxes being put on goods.
What took so long? The UK voted to leave the EU in 2016 and actually left on 31 January 2020, but leaders had until the end of 2020 to work out a trade deal.
There are big changes ahead. Although it's a trade deal that has been agreed, there will also be changes to how people travel between the EU and UK, and to the way they live and work.
Tyurkyan Osmanova from Shumen, Bulgaria... now living in Cambridge, England
Back home, I was a journalist for Bulgarian National Radio and had two university degrees. But I followed my husband to the UK eight years ago.
Usually, when somebody moves to a different country it's for study, work or to seek a better future. For me, it was a mixture of all of them.
It hasn't been easy, but I started a business offering accounting services and now I have an office in Cambridge and a good portfolio. A few months ago, I applied for British citizenship because I'd like to spend the rest of my life here and provide a future for my children in this country.
We were worried about the uncertainty of a no-deal Brexit, so we welcomed the trade deal like a Christmas present. Many people are breathing a sigh of relief over that!
But we still don't know the real parameters of the deal and I think it will take time for it to settle and be put into action.
My husband has a food business, and he's worried about how the deal will affect the prices of goods and supplies. Sadly, lots of small businesses are giving up because they feel double pressure from Brexit and the coronavirus pandemic.
It will be a challenging time for all of us.
Alyson Sheldrake from Devon, England... now living in the Algarve, Portugal
I'm a former director of education at the Church of England and my husband, Dave, is a retired police officer. We bought a house in the Algarve in 2006 while still living and working in the UK, but once Dave retired in 2011 we moved here permanently.
One of our main concerns was that everything was left unresolved for so long. It left everyone in limbo, not knowing what might happen or what the future might look like.
We've had to accept that whatever deal was struck would negatively influence us and our financial position. The pound-to-euro rate plummeted as soon as the Brexit vote was announced, and it hasn't moved much since.
There are broader concerns than just our own lives to consider, though. As a former educator, I'm aware of the benefits programmes like the Erasmus scheme bring to young people.
I guess it's better to have a trade deal in place than not having one, but people are already talking about tariff wars in the future and they haven't even started sorting out what this means in terms of transporting goods.
Personally, I'm intent on bringing my Portuguese language skills up to the required level to apply for citizenship. We're settled and very happy here.
Bibiana Jordan-Horvath from Krompachy, Slovakia... now living in Sheffield, England
I've been living in the UK since the 1990s, when I first came to study English as a foreign language in Salisbury.
I now teach English and work with Czech and Slovak communities in Sheffield and elsewhere. I've definitely noticed panic over Brexit among many people who thought of themselves as established Europeans in this country.
All of us were anxious about jobs, living costs, and how businesses and free movement could be affected.
But I'm definitely pleased a trade deal was agreed. I felt prolonged anxiety during the negotiations, and the coronavirus pandemic didn't help with this! I also think it showed the importance of countries standing together.
We'll have to turn this moment into opportunities and advantages. Let's embrace this change.