Millions watch New Year fireworks
Millions of revellers have seen in the new year with fireworks spectaculars in London and Edinburgh dazzling crowds.
Thousands gathered along the Thames to see an 11-minute display centred on the London Eye, accompanied by an electronic soundtrack and followed by Auld Lang Syne.
Ticketing was introduced for the first time in London, with numbers kept to 100,000, down on the estimated 500,00 last year.
Up to 75,000 people gathered in Edinburgh for the world-famous event which saw Lily Allen headline the Concert In The Gardens.
The London display was counted in by a 10-minute digital countdown on The Shard's western facade, followed by lighting comprised of searchlights, strobes, and a 2015 numeric graphic.
The display itself included 5,500 fireworks cues, 2,000 lighting cues, 12,000 fireworks producing 50,000 projectiles, and 30 tonnes of equipment on the three fireworks barges situated on the river in front of the London Eye, according to the Greater London Authority.
Mayor of London Boris Johnson said: "Tonight's dazzling celebrations have shown London at its best.
"I hope everyone who attended and watched from home, here in the UK and across the globe, were as impressed with this fabulous showcase for our great city. The success of this huge event is down to the hard work of all those involved, including the Met Police, emergency services, TfL, local authorities and many others that made sure everyone enjoyed their evening and got home safely.
"A great start to 2015, I'd like to thank everyone involved and wish you all a very happy new year."
The London ticketing scheme was brought in following consultation with the Metropolitan Police, emergency services, and local authorities, to help manage crowd numbers which have been growing each year.
Since first being staged at the London Eye on the South Bank in 2003, the numbers heading to see the pyrotechnic and lighting display have increased from an estimated 100,000 people in its first year to around 500,000 last year, putting enormous strain on transport, infrastructure and the ability of the emergency services to move around.
The Metropolitan Police said 4,000 officers worked on the New Year's Eve celebrations and by 6am some 90 people had been arrested.
They included 27 for being drunk and disorderly, 22 for assault, seven for sexual offences, six for drugs and two for possession of an offensive weapon.
Superintendent Robyn Williams said: "This year saw a change to proceedings with the fireworks ticketed. Our advice to the public was to avoid the area unless they had a ticket and they appeared to take this on board as we have seen lower numbers than in previous years.
"Officers worked hard, alongside stewards, to keep people safe during the event and ensure that everyone who came into central London to enjoy the fireworks was able to make their way home at the end of the night.
"The event passed off safely and appeared to be enjoyed by the crowd - the primary objectives of the operation."
Officers worked through the night to facilitate the clean up operation and bring the area back to normality in time for the New Year's Day parade.
Ambulance services also experienced a busy night although London Ambulance Service (LAS) saw a 21% drop in calls across the capital compared to last year.
Between midnight and 5am the control room took 2,042 calls. Last year's figure was 2,588.
At peak times emergency call takers answered around 450 calls an hour, compared to over 600 last year.
East of England Ambulance Service also received fewer calls than 12 months ago.
Some 1,616 emergency calls were received between 7pm and 5am, compared to 1,737 over the same period last year.
In Edinburgh, thousands took part in the huge outdoor celebrations before the clock struck midnight, with Lily Allen joined by special guests Bjorn Again and Soul II Soul.
The celebrated party also saw performances from Twin Atlantic, Twilight Sad, Eddi Reader and this year's Mercury Prize-winners, the Edinburgh-based act Young Fathers.
The traditional outdoor ceilidh also saw 3,000 people dancing through the midnight bells.
Elsewhere, celebrations at Stirling Castle's esplanade were cancelled due to high winds.
Across the Atlantic, New York saw about one million revellers gather in Times Square to watch a giant, glittering ball drop as a ton of confetti containing well wishes for the upcoming year fell upon them.
Former foreign secretary David Miliband was among those who pushed the button to set the ball on its way.
The brother of Labour leader Ed was there on behalf of the International Rescue Committee (IRC), which was the philanthropic partner of the event.
Mr Miliband, who is president and chief executive of the organisation, was joined by models and ex-refugees Alek Wek and Nykhor Paul.
Writing in the New York Daily News, Mr Miliband said "the new year cannot come soon enough" for people served by IRC around the world.
"New York will send a message that it has not forgotten its roots in immigration, its values of providing shelter for poor and huddled masses or its commitment to send a message of compassion and humanity around the world," he added.
Celebrations in China were marred after 36 people were killed in a stampede in central Shanghai, which occurred half an hour before midnight in the popular riverfront Bund area.
Tourist Rebecca Thomas, from Manchester, described how she saw people being resuscitated on the ground.
She told BBC News: "CPR was being given to 10-15 people in the street by loved ones whilst police stood by and watched.
"I asked a police officer if I could help and was told to move along. I saw a man giving his wife or girlfriend mouth-to-mouth on the floor whilst police watched."