The world has begun marking the start of 2016, with Kiribati the first nation to ring in the new year.
More than one million people gathered along the famed harbour in Sydney to watch a 12-minute fireworks display featuring a multicoloured firework "waterfall" cascading off the Harbour Bridge and pyrotechnic effects in the shapes of butterflies, octopuses and flowers.
Thousands also gathered in Melbourne, where 11 tonnes of fireworks were set off.
New Zealand, the first country with a sizable population to celebrate the beginning of 2016, counted down to midnight with a giant digital clock on Auckland's Sky Tower.
Horns sounded and crowds cheered as the tower was then lit up with fireworks, with colours changing from green to red to white.
Filipino Catholic devotees jostle to get closer to the image of the Black Nazarene during a thanksgiving procession on New Year's eve in Manila, Philippines. Image: Bullit Marquez / AP/Press Association Images
A woman prays in front of lanterns to celebrate the new year at Chogye Buddhist temple in Seoul, South Korea. Ahn Young-joon / AP/Press Association Images
An Indian man releases balloons with a placard during a function to welcome the new year at a school in Ahmadabad, India. Image: Ajit Solanki / AP/Press Association Images
Information about just some of the events taking place in Ireland tonight can be found here.
The iconic Times Square New Year's Eve Ball will feature 288 new Waterford Crystal triangles this year when it descends at around 5am Irish time tomorrow morning.
Around one million revellers will converge in the New York square.
Brussels has cancelled its official fireworks display after two men were arrested by police and accused of plotting to attack the event in Belgium's capital.
Paris has also called off its traditional display in the Champs-Elysees as it remains on high alert following last month's terror attacks.
The French capital will also have 11,000 officers patrolling the city compared with 9,000 last year.
In London, extra armed officers have been called in to police the New Year's Eve celebrations later.
Officials in Las Vegas have urged people to leave bags, backpacks and buggies at home as police prepare for hundreds of thousands of partygoers to flood the Las Vegas Strip.
The huge party on Rio de Janeiro's Copacabana Beach will have two themes: the 100th anniversary of samba music and the upcoming Olympics, which the Brazilian city will host in August.
More than two million people are expected to converge on the beach.
Security has also been increased in Malaysia's biggest city, Kuala Lumpur.
There, fireworks will ring in the New Year at a historical square as well as at the Petronas Twin Towers, one of the world's tallest towers.
In the Philippines, stray bullets and exploding firecrackers have killed one person and injured almost 200 others as the country celebrates the beginning of 2016.
In Japan, New Year's Eve is the nation's biggest holiday, with millions expected to leave the cities and head to their hometowns.
As midnight approaches, many families visit neighbourhood temples, where huge bronze bells are rang.
China is planning an official celebration near Beijing's Forbidden City, which will include performances and fireworks. A gala will also be held at the Bird's Nest stadium.
In Thailand, tens of thousands are expected to mark the start of 2016 at the same intersection where a pipe bomb killed 20 people.
Up to 5,000 police will be in the area around the Erawan Shrine in Bangkok, with explosive ordnance disposal experts making a sweep beforehand.
