Thousands of people gathered in London to see in the new year by remembering some of the most best moments of 2012, with clips from the 2012 Olympic Games featuring in an 11-minute fireworks display over the London Eye.
Mayor of London Boris Johnson said: "What an amazing end to an incredible year.
"Watched by hundreds of thousands in the capital and millions around the globe, London has proved, yet again, that it can pull off spectacular world-class events in style."
London put on a spectacular display to end an incredible year for the city
About 250,000 people were estimated to be in the capital to watch the colourful and noisy display, which featured 12,500 fireworks.
Many of them waited for hours to secure the best viewpoints on the banks of the Thames, but fortunately it was a dry and mild night.
Rob Haine, 30, a computer game programmer from Wakefield, said: "The display was mesmerising, it was a joy to witness.
"I had high expectations but they were completely surpassed.
"I got here at 5pm and have been standing the whole time but it was worth it. It was cool that they got the Olympics into the fireworks."
Sandro Benvenuti, 46, travelled from Italy with his wife and two daughters to see the display.
"We were waiting for six hours but it was fantastic," he said.
"We have fireworks in Italy but those were much better. They went on for longer and the design and special effects were superior."
Lynn Shepherd, 53, from the village of North Newbald, East Yorkshire, praised the "electric atmosphere".
She said: "There's no trouble here. Everyone is having a good time and it's the perfect way to finish 2012."
The Metropolitan Police said as of 3.45am, officers made 96 arrests across the capital relating to the New Year's Eve celebrations, mainly for being drunk, public order offences and assault.
More than 3,500 police supported the organisers and stewards of the event in central London, working alongside colleagues from the British Transport Police and other emergency services to keep revellers safe.
Chief Inspector John Williams said: "This year has really been one to remember and what better way to top off the success of team GB at the Olympics and Paralympics and the pageantry of the Queens Diamond Jubilee than with a world-class firework display.
"This year saw the viewing areas fill up earlier than ever before with thousands of revellers coming to see in the new year London-style.
"Officers worked hard, alongside the stewards, in very large crowds to keep people safe in what is a challenging policing environment, helping to ensure revellers and visitors alike could make their way home at the end of the night.
"There were no major issues reported to police and the crowds were good natured.
"Officers continue to work through the night to facilitate the clean-up operation, ensure roads are reopened and the area returns to normality in time for the New Year's Day parade."
Earlier that day, New Year's Eve celebrations had already started on the other side of the world, with revellers in Australia and New Zealand the first to welcome in 2013.
Thousands of people thronged the streets in Sydney, Australia, to see singer and actress Kylie Monogue set off the city's famous firework display over the iconic Harbour Bridge as midnight struck.
Some 1.5 million people were predicted to watch the fireworks in Sydney, and an estimated one billion people around the world.
The Sydney extravaganza was preceded by an impressive fireworks display from Auckland in New Zealand. Crowds thronged the city cetnre to watch the event at the city''s Sky Tower.
Spectators watch as fireworks light the Quezon Memorial Circle in Manila, Philippines
The revelry in Australia was soon followed by events in Hong Kong, where AFP reported 100,00 people watched an eight-minute display around Victoria Harbour. Firework shows also took place in Beijing and Shanghai.
For the first time under military rule, Burma enjoyed new year's celebrations with fireworks in the former capital Rangoon, while footage from North Korea showed public celebrations in the capital, Pyongyang.
However, celebrations were muted in India following the death of a woman who was gang-raped earlier this month.
Clubs, politicians and the armed forces called off celebations as a mark of respect for the 23-year-old, who died on Saturday, two weeks after the attack on a bus in Delhi.
Pope Benedict XVI celebrated New Year's Eve vespers by voicing solidarity with the poor and calling on believers to pause to reflect from time to time despite busy lives, AFP reported.
"We have to know how to stop and think. This way our soul can find healing for the inevitable wounds of everyday life," he said.
In spite of the scenes of blue skies, beaches and hot weather, the best place to celebrate New Year's Eve is not the land down under, according to a survey.
Social networking site Badoo.com found most people would like to see out the end of the year with Brazilians, the Sydney Morning Herald reported.
In the capital, crowds had been steadily growing in anticipation of the fireworks display centred around the London Eye.
However, the celebrations were marred by the death of a Spanish tourist earlier in the day.
The 48-year-old woman, her daughter and son were all hit by a bus on Sunday afternoon and taken to hospital where she died on Monday, police said.
Her daughter, 18, remains in a serious but stable condition, and her son, 11, is in a stable condition.
The woman's husband was with them at the time of the incident but was uninjured.
A few hours before the UK's festivities, there were incredible scenes from Dubai where the world's tallest building, the Burj Khalifa, was the centrepiece of a stunning fireworks display accompanied by the Prague Philharmonic Orchestra.
London welcomes 2013:
London Celebrate's New Year's Eve
Celebrations from around the world: