New Year revellers across the UK fell silent to remember those killed in the Asian tsunami disaster.
Celebrations were toned down in the wake of the tsunami
Friday night's celebrations in London were toned down because of the tragedy, and there was a two minutes' silence just before Big Ben chimed at midnight.
A 10-minute lighting display that had been scheduled to go ahead in the run up to midnight was cancelled.
In Edinburgh, partygoers observed a one-minute silence at 2245 GMT. Glasgow fell silent at 2215 GMT.
Silences were also held in towns and cities across Northern Ireland.
About 150,000 people gathered on the South Bank of the River Thames for the £1m London event, according to police.
Despite the celebrations being toned down, a spectacular firework display lit up the
London Eye to mark the start of 2005.
It certainly impressed some visitors, with Adriana Montserrat, 26, from Mexico City, saying: "It was the best New Year of
my life. I have never seen anything like it."
Ray Levell, 56, from Croydon, said: "It was excellent, a lot better than last
year. There was a lot more in it. It was great that the crowd respected the
Hundreds of thousands partied in Edinburgh
During the London celebrations, the number for people to call to make donations to the UK's Asian tsunami fund was flashed across big screens.
Ahead of the firework display, Mayor Ken Livingstone said: "Tonight London will remember all of those killed by the tsunami in Asia and beyond and pledge that we will do everything in our power to assist the relief effort for those now living in catastrophic conditions.
"Our hearts go out to the thousands of Londoners and other people throughout the world who have lost family members and friends as a result of this calamity."
In Edinburgh, more than 250,000 people celebrated Hogmanay on the streets, with an outdoor concert and street party in Princes Street.
Last year, celebrations were called off at the last minute in Edinburgh, Aberdeen, Liverpool and Newcastle because of bad weather.
But this year's celebrations went ahead as planned.
In Edinburgh, several bands played to 100,000 ticket-holders.
At midnight 150,000 more people took to the streets to watch fireworks by Christophe Berthonneau, who masterminded the Eiffel Tower Millennium and the Athens Olympics displays.
Outdoor parties were also held in Aberdeen, Glasgow and Stirling.
About 150,000 gathered in London for the New Year's Eve fireworks
In Glasgow, 25,000 turned out for its celebrations in George Square, while in Aberdeen 40,000 people watched Scottish acts Deacon Blue, Hue and Cry and Fame Academy winner David Sneddon.
And in Cardiff, more than 50,000 people gathered in the streets around the civic centre to watch bands, take a turn on the fairground rides or take to the ice in the council's Winter Wonderland rink.
The festivities marked the start of the city's year-long centenary celebrations.
Cardiff's 100th birthday as a city falls on 28 October 2005.
In south London, members of the Tamil community used the usual New Year parties at cricket clubs to help tsunami victims in Sri Lanka.
Latha Vipulananthan, 31, an IT support technician from Enfield, visited Surbiton Cricket Club.
"This year, rather than having dancing, they all brought donations and clothing. Air Lanka has said, because of all the empty seats, they will take goods given to them across free of charge," she said.
Despite the thousands on the streets of cities, a survey earlier this week had suggested many people were planning a quiet evening in.
According to the Mint survey, almost eight out of 10 had been put off by high prices in clubs and bars as well as public transport difficulties, and would not go out to celebrate.