Fireworks illuminated skies over Paris, Rio and Sydney to celebrate the entry to 2024, while in Israel, Gaza and Ukraine, rockets and strikes marked the year's earliest hours.
Much of the world's population -- now more than eight billion -- is hoping to shake off high living costs and global tumult in 2024, which will bring elections concerning half the world's population and the Paris Olympics.
But with the new year barely started there were already ominous signs: at the stroke of midnight in Gaza a barrage of rockets was fired towards Israel -- a twisted reflection of the fireworks lighting up night skies elsewhere around the world.
In New York City, thousands of visitors lined up for a chance to see the annual dropping of a giant illuminated ball in Times Square.
Nearby stallholders hawked vuvuzelas and 2024-branded hats as police fanned out across central Manhattan, towing suspicious cars, closing roads and manning a ring of steel screening would-be revelers.
Hours earlier, more than a million partygoers had packed in around the harbor in Sydney, the self-proclaimed "New Year's capital of the world," to watch eight tonnes of fireworks.
Pyrotechnics also illuminated the skies in Auckland, Hong Kong, Manila and Jakarta.
Nudist bathers wearing Santa hats waded into the mild waters of southern France, while revelers danced in the streets in Greece's Thessaloniki.
In Denmark, popular Queen Margrethe II, Europe's longest-serving monarch, chose her New Year's Eve address to announce her coming abdication.
The 83-year-old monarch will step down in favor of her son, Crown Prince Frederik, after 52 years on the throne.
The last 12 months brought "Barbenheimer" to the box office, a proliferation of human-seeming artificial intelligence tools, and a world-first whole-eye transplant.
India outgrew China as the world's most populous country, and then became the first nation to land an unmanned craft on the Moon's south pole.
It was also the hottest year since records began in 1880, with a spate of climate-fuelled disasters striking across the world.
Fans bade adieu to "Queen of Rock 'n' Roll" Tina Turner, "Friends" actor Matthew Perry, hell-raising Anglo-Irish songsmith Shane MacGowan, and master dystopian novelist Cormac McCarthy.
- Rebuilding -
2023 will be remembered for war in the Middle East, after Hamas's unprecedented October 7 raids on southern Israel and Israel's ferocious reprisals on Gaza.
The United Nations estimates that almost two million Gazans have been displaced since Israel's siege began, or about 85 percent of the peacetime population.
With once-bustling Gaza City neighborhoods reduced to rubble, there were few places left to mark the new year -- and fewer loved ones to celebrate with.
"It was a black year full of tragedies," said 37-year-old Abed Akkawi, who fled the city with his wife and three children to a UN shelter in Rafah, southern Gaza.
"God willing this war will end, the new year will be a better one, and we will be able to return to our homes and rebuild them, or even live in a tent on the rubble," he told AFP.
In Tel Aviv, Israel, 24-year-old Ran Stahl preferred to work his shift at a wine bar during New Year's Eve, saying he didn't have the heart to celebrate.
"The minute I start dancing, the sadness and mourning come back," said Stahl, whose friend died at the trance music festival during Hamas's October 7 attack.
Some in Vladimir Putin's Russia were also weary of conflict, this time in Ukraine.
"In the new year I would like the war to end, a new president, and a return to normal life," said 55-year-old theatre decorator and Moscow resident Zoya Karpova.
But Putin himself remained bullish in his New Year's Eve address, vowing that Russia "will never back down".
Ukrainian President Volodymyr Zelensky's New Year's Eve address, after nearly two years of war, was defiant.
Ukrainian pilots were mastering the F-16 warplanes supplied by their allies, he said. In 2024, "we will definitely see them in our skies. So that our enemies can certainly see what our real wrath is."
Russia would also feel the full force of Ukraine's domestic arms production, he added, including at least a million drones.
In Rome, Pope Francis prayed for the victims of conflicts around the globe, including the people of Sudan and the "martyred Rohingya" of Myanmar.
"At the end of a year, have the courage to ask how many lives have been torn apart in armed conflicts, how many deaths?" the 87-year-old pontiff said after his Angelus prayer in St Peter's Square.
"And how much destruction, how much suffering, how much poverty? Those who have an interest in these conflicts, listen to the voice of conscience."
- To the polls -
Several pivotal elections are scheduled in 2024, with the political fate of more than four billion people to be decided in contests that will shape Russia, Britain, the European Union, India, Indonesia, Mexico, South Africa, Venezuela and a host of other nations.
But one election in particular promises global consequences.
In the United States, Democrat Joe Biden, 81, and Republican Donald Trump, 77, appear set for a November rerun of their divisive 2020 presidential contest.
Biden marked the new year by proclaiming optimism for the US economy -- and his well-known love for chocolate-chip ice cream.
In a televised appearance ahead of the New York celebrations he touted his country's resilience after the pandemic, announcing that the American people "are back."
As the incumbent, Biden has at times appeared to show his age and even supporters worry about the toll of another bruising four years in office.
There are at least as many concerns about a Trump return.
He faces prosecution on several counts, and 2024 could determine whether the bombastic self-proclaimed billionaire goes to the Oval Office or jail.
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