New Year's celebrations across the world have ushered in 2017 with dazzling fireworks displays and crowded streets amid tightened security measures for the festivities.
There was a huge police presence on the streets of London as spectators from nearly 100 countries flocked to the Thames to watch the night sky light up as Big Ben struck midnight.
With memories of the lethal Berlin lorry truck attack still fresh, London mayor Sadiq Khan assured crowds the capital was "as safe as it possibly can be".
In Scotland, Hogmanay celebrations were expected to attract a crowd of up to 80,000 people to Edinburgh for the sold-out, world-famous event, described as the UK's largest outdoor winter festival.
Cities in the Pacific island nations of Samoa, Tonga and Kiribati were among the first to bid farewell to 2016, before fireworks were launched from the top of Auckland's Sky Tower.
Two pyrotechnic shows followed at Sydney Harbour and doused Australia's iconic bridge in the bright light of an estimated seven tonnes of fireworks.
The city's display also saw Sydney Harbour Bridge turned purple in a tribute to Prince, while David Bowie was honoured with space-themed visuals in a nod to the late star's hit, Space Oddity.
Meanwhile, red starbursts exploded above the Kremlin for the Russian occasion, which marks the country's major gift-giving holiday.
In Europe, fireworks in Helsinki also signified the beginning of the centenary year of Finnish independence.
Mr Khan said the mood on the streets was "upbeat", adding it was "really important we don't allow terrorists to disrupt our celebrations on this New Year's Eve".
Speaking ahead of 2017's arrival, he told the Press Association: "It's as safe as it possibly can be.
"We've done everything we possibly can do to keep us safe. We've got more armed police officers on duty tonight than we have on any previous year."
Around 3,000 officers were on duty within and outside ticketed areas, while armed police were also set to be a fixture on the capital's Tube trains as they travel between jobs in a move aimed at reassuring passengers.
Fears of a mass-casualty terror plot targeting one of the country's New Year events heightened after lorries were used in devastating attacks on crowded areas in Nice and the German capital.
British Transport Police (BTP) said it would also be extending officers' working hours on the night for a second year running.
BTP Superintendent Andy Morgan said: "We developed and improved our security plan for last year's New Year's Eve event following the atrocities in Paris in the previous November and we, of course, have looked at good security, a thorough security boost following a different type of threat in Nice back in July."
Some anticipated the arrival of the New Year on boats that darted back and forth in front of the London Eye, which projected rainbow spotlights from its base, while crowds lining the Victoria embankment held their phones aloft with the torches on to illuminate the shoreline.
The site's DJ acknowledged international visitors and said they were welcome to the capital to kick off 2017, with music keeping them entertained in the hours leading up midnight.
As the UK marks the start of 2017, other regions of the world will still be waiting for the much-anticipated stroke of midnight.
The new year will not arrive in New York until 5am London time on Sunday, while places such as Baker and Howland Island will be the last to ring it in at about midday (GMT).