Revellers across the UK have rung in the start of a new decade, with fireworks displays in London, Edinburgh and other major cities.
In London, some 12,000 fireworks lit up the capital’s skyline.
The UK’s “biggest street party” had been promised for Edinburgh as part of the city’s Hogmanay celebrations.
Firework shows are also being held in other cities including Manchester, Cardiff, Newcastle, Inverness and Nottingham.
In London, Big Ben’s chimes sounded the start of the display, despite them being silent this year while renovation work is completed.
Around 100,000 revellers packed into the streets around Victoria Embankment as the roar of football anthems such as Three Lions kicked off the new decade, with the festivities providing a prelude to the Euro 2020 football tournament.
Music from artists including Stormzy, Wiley and Bastille also featured in a display London Mayor Sadiq said would be the best the capital “has ever seen”.
“We may be leaving the European Union, but we’re not leaving Europe. So tonight’s fireworks celebrate us as a global city, us as a European city,” he added.
He stressed that London and the UK need to be brought “together again” in the 2020s.
“I’m not pretending that fireworks and one night can do that, but I think it’s really important [that] we celebrate, tonight, some great things about our city and our country,” he said.
In Edinburgh fireworks have been let off from the castle.
Musical artists including DJ Mark Ronson, Idlewild, Rudimental and Marc Almond have been performing on stages throughout the city centre.
Tens of thousands of people are expected to attend the street party, which covers at least part of more than a dozen streets in the city centre.
The evening has been cold but dry for many, with temperatures in Scotland and parts of northern England forecast to be around 1C (33.8F) or 2C (35.6F), according to the Met Office.
The rest of the UK is likely to see the mercury fall to around 5C (41F).
A yellow weather warning for fog has been issued by the Met Office for parts of north-eastern England. The warning is in place from 19:00 GMT on New Year’s Eve until 03:00 GMT on New Year’s Day.
Parts of central England could see some drizzle on Tuesday evening while there may also be patches of fog appearing across the UK, according to Met Office forecaster Greg Dewhurst.
The first places to welcome 2020 included the tiny Pacific island of Kiribati, neighbouring parts of Samoa and the Chatham Islands.
Auckland in New Zealand was the first major city to ring in the new decade, with thousands welcoming 2020 at a fireworks display at the city’s Sky Tower.
The traditional fireworks display in Sydney Harbour also went ahead, despite calls for it to be cancelled due to Australia’s bushfire crisis.
European cities, including Paris, Berlin, Madrid and Athens, have also seen in the new year with firework displays.
The uninhabited Baker Island and Howland Island, on the other side of the International Date Line, will be the last to leave 2019 behind.