Celebrations were taking place amid tight security as such cities as Sydney and Paris feared repeats of recent ethnic riots and authorities were on guard against terror attacks. In Indonesia, a bomb killed eight people and wounded 45 at a market crowded with holiday shoppers.
Workers in London's subway system began a 24-hour strike at midday Saturday, complicating travel plans for revelers preparing to celebrate the new year across the city, including at a huge open-air party in Trafalgar Square.
Families in Sydney trooped to vantage points around the harbor to watch a spectacular fireworks show that began at midnight.
The message of love in the celebration, however, went hand-in-hand with a huge police presence aimed at preventing a repeat of mid-December's two nights of racial violence in beach suburbs. More than 1,700 officers were on duty and police helicopters and boats buzzed about the harbor.
The generally jubilant celebration was in sharp contrast with last year, when the devastation of the Indian Ocean tsunami led many countries and individuals to cancel festivities.
"It's a bit hard to celebrate when you see people so dejected and hurt, like what people saw on TV. This year is much better," said Ann Ward from the Blue Mountains west of Sydney, who brought her family to watch the fireworks display.
In Brazil, more than 2 million people are expected to arrive at Rio de Janeiro's famed Copacabana Beach to watch a New Year's Eve fireworks extravaganza that officials said would be the largest in the city's history. They planned to set off nearly 25 tons of fireworks.
For the millions left homeless by this year's South Asian earthquake, however, the new year was expected to begin with heavy snow and rain. Relief agencies warned that the harsh Himalayan winter could hamper aid deliveries and create conditions ripe for illnesses.
Pakistan's army and aid workers have been using helicopters, trucks and mules to get tents, clothes, food and other provisions to survivors since the Oct. 8 quake killed an estimated 87,000 people and destroyed the homes of 3.5 million more.
In Indonesia's Central Sulawesi province, a bomb ripped through a busy meat market in a predominantly Christian district Saturday, killing at least eight people and wounding 45, officials said. Police said the bomb packed with ball bearings and nails went off as people bought pork for the night's festivities.
The attack in Palu followed repeated warnings from Indonesian authorities that the al Qaeda-linked militant group Jemaah Islamiyah was plotting holiday attacks in the world's most populous Muslim nation.
Some 5,000 security officers in mostly Muslim Bangladesh searched cars in the capital hoping to avoid a new attack in a series of bombings blamed on Islamic extremists that killed at least 26 people. Police patrolled Dhaka's entertainment districts, college campuses and wealthy residential areas, where Western-style new year's celebrations often end in drunken revelry.
In France, 25,000 police officers were assigned to keep order on New Year's Eve, a night when partying youths often set hundreds of cars ablaze as festivities get out of hand.
Police were especially cautious this year because of the rioting and car burnings that raged for three weeks starting in late October, primarily among disaffected Muslim youths in poor suburbs. A state of emergency imposed to quell the rioting remains in effect.
In the Philippines, officials threatened to arrest anyone who set off powerful fireworks or fired guns, seeking to cut down on the deaths and injuries that accompany New Year's Eve festivities every year.
At least two Filipinos died from guns fired in celebration and two deaths were reported from people accidentally eating a popular candy-looking sparkler. An additional 162 suffered firework-related injuries during the run-up to the holiday, officials said.
In Japan, police expected more than 14,000 people to climb the country's mountains, including the 12,387-foot, snowcapped Mount Fuji, to see the first sunrise of the new year. Some 100 million people were likely to visit shrines and temples in the first three days of 2006.
But a new holiday pastime also has emerged among Japanese--watching professional wrestling on TV--and many rang in the new year glued to their sets.