New Year celebrations: Crowds turn out to see in 2013
Large crowds turned out for spectacular firework displays across the UK, as the new year was welcomed in with a bang.
The centrepiece of the celebrations saw a quarter of a million people line the banks of the River Thames for a huge display set around the London Eye.
Almost 13m people watched that display on television, figures suggested.
In Edinburgh, another colourful array of pyrotechnics lit up the castle as crowds of about 75,000 people sang Auld Lang Syne to herald the start of 2013.
In Northern Ireland, a huge fireworks display marked the beginning of the Derry-Londonderry 2013 City of Culture year.
And UK forces in Afghanistan celebrated with pipe music and party poppers.
In the aftermath of the celebrations, more than 500,000 people turned out for London's New Year's Day parade, with a starring role for 400 Olympic Games Makers.
They, along with a procession of performers and dignitaries, marked the end of a year that saw the city host the Olympic and Paralympic Games and the Queen's Diamond Jubilee celebrations.
These major events of the year also featured strongly in Monday night's celebrations in London.
As 12,500 fireworks lit up the night sky above the English capital during the 11-minute display, memorable clips from the Games and Jubilee played out.
Many spectators had waited for hours for the spectacular but many more tuned in to watch the show on television, with initial figures suggesting 12.9m people watched the display on BBC One.
London Mayor Boris Johnson described the night as "an amazing end to an incredible year".
In other developments:
- Police in London say 96 people were arrested, but there were "no major issues", while the ambulance service say they saw a "significant rise" in people needing treatment during London's celebrations compared with last year
- Hogmanay organisers say there were four arrests after the celebrations in Edinburgh
- In Blackpool, coastguards say a 41-year-old man who was swept into the sea just after midnight is unlikely to have survived
- Three merchant seamen were rescued after drifting in a broken down boat off Anglesey for three hours following New Year's Eve celebrations
- Ambulance crews in the South East saw a major increase in callouts on New Year's Eve compared with last year
- Some 200 New Year's Day swimmers in Whitley Bay, North Tyneside, braved the cold water, as did swimmers at a lake near Bristol
- Thousands of people packed into Newcastle city centre to bid a colourful farewell to 2012 with a winter carnival
- The Archbishop of Canterbury paid tribute to unsung volunteers in his final new year message
Rob Haine, 30, a computer games programmer from Wakefield, described the London display as "mesmerising".
Sandro Benvenuti, 46, who travelled from Italy with his wife and two daughters to see the display, said: "We were waiting for six hours but it was fantastic."
Lynn Shepherd, 53, from North Newbald, East Yorkshire, said the atmosphere was "electric".
She said: "There's no trouble here. Everyone is having a good time and it's the perfect way to finish 2012."
Downpours had earlier threatened to dampen the celebratory mood - but many revellers braved the rain in Scotland, Northern Ireland and eastern England.
In Edinburgh, Scottish rock band Simple Minds headlined the Concert in the Gardens, where they were joined by The View and Bwani Junction against the backdrop of Edinburgh Castle.
Joanna White and a group of friends travelled from Melbourne and Adelaide in Australia to experience their first Hogmanay in Edinburgh.
She said: "We love Hogmanay, we want to come back here every year. It's been awesome.
"There are a lot more people here than we thought, and there's people from everywhere."
Brian Forbes, from Machynlleth, Wales, who was also in Edinburgh at new year for the first time, said: "The organisation has been fantastic and everyone is so friendly."