Australia's opposition has crushed the governing Labor party in a general election that has returned the Liberal-National coalition to power for the first time in six years.
Early projections show Labor winning 55 seats compared with the coalition's 91.
Liberal leader Tony Abbott said he looked forward to forming a competent and trustworthy government.
Prime Minister Kevin Rudd earlier admitted defeat and said he would not stand again for the Labor leadership.
The main election issues were the economy, reducing the number of asylum seekers arriving by boat, and a tax on carbon emissions.
Mr Rudd called the election after defeating Julia Gillard in a leadership challenge in June, amid dismal polling figures that showed Labor on course for a wipe-out.
Under Mr Rudd, Labor initially saw its figures improve. But Mr Abbott, who enjoyed the strident support of Rupert Murdoch's newspapers, then widened the gap again.
"From today I declare Australia is under new management and Australia is now open for business", Mr Abbott told a cheering crowd as he delivered a victory speech.
He said that he would put the budget back into surplus, and boats bringing migrants from Asia would stop.
He added that support for Labor was at its lowest ebb for 100 years, and said the results showed that the Australia people would punish anyone who took them for granted.
Mr Rudd said he had phoned Mr Abbott and wished him well.
"I gave it my all but it was not enough for us to win," he said. But he was pleased that Labor was preserved as a "viable fighting force for the future".
Mr Rudd retained his seat in the Brisbane constituency of Griffith but said he would not re-contest the Labor party leadership because the Australian people "deserve a fresh start".
"I know that Labor hearts are heavy across the nation tonight. As your Labor leader I accept it as my responsibility," he said.
With two-thirds of the votes counted, the Australian Broadcasting Corporation said the coalition had secured 85 seats in parliament and was on course to win 91. Labor had secured 54, with a predicted final tally of 55.
In the previous parliament, Labor relied on the support of independents and the Greens for its minority government, with 71 seats to the coalition's 72.
Mr Abbott took on the leadership of the flagging Liberal-National coalition in 2009.
A Rhodes scholar who once wanted to be a Roman Catholic priest, Mr Abbott has pledged to repeal both the mining and carbon taxes introduced by Labor.
He has also promised a raft of budget cuts, including reducing the foreign aid budget by A$4.5bn ($4bn, £2.6bn).
But he says he will fund an expanded paid parental leave scheme.
Mr Abbott will be charged with managing the transition as the mining and resources boom subsides, amid slowing demand from China and slumping commodity prices.
Ahead of the polls, his coalition highlighted bitter Labor infighting, seeking to portray itself as the more stable party.
And former Labor Prime Minister Bob Hawke blamed the internal divisions for Labor's defeat.
"I really believe this was an election that was lost by the government rather than one that was won by the opposition," he said.
Julia Gillard, meanwhile, congratulated the Labor candidate who succeeded her in her seat, as she bowed out of politics.
And in something of an upset, billionaire Clive Palmer - who founded the fringe Palmer United Party - appeared on course to win a seat in parliament.
More than 14 million people were expected to vote in Saturday's election. Voting is compulsory in Australia.
Tony Abbott - Profile
When Tony Abbott took over Australia's flagging Liberal-National coalition in December 2009, his election raised a few eyebrows.
A former Rhodes Scholar who once wanted to be a monk, Mr Abbott was a polarising figure, especially at the start of his leadership.
He attracted early criticism for gaffes and was famously called a misogynist by former Labor Prime Minister Julia Gillard in a fiery parliamentary speech.
But, amid bitter Labor infighting, Mr Abbott gradually transformed his image in the eyes of many from that of pugnacious politician to leader-in-waiting.
He took on Kevin Rudd - who ousted Ms Gillard as Labor leader - in the 7 September 2013 polls and secured a convincing win to become Australia's prime minister.
'Mad monk'
Tony Abbott was born in 1957 in England to Australian parents who returned to Sydney a few years later.
After graduating in economics and law from the University of Sydney, where he was also a leading student boxer, he attended Oxford as a Rhodes Scholar, studying politics and philosophy.
He briefly trained as a Catholic priest, before working as a journalist for The Australian newspaper.
He then worked as an adviser to the Liberal Party, before entering politics in 1994 when he was elected to represent the affluent Warringah district of Sydney.
Under former Prime Minister John Howard's government, he served as an employment minister between 1998 and 2001, and as minister for health and ageing in 2003.
In 2009, he narrowly beat then leader Malcolm Turnbull in a party leadership vote, winning 42 votes to Mr Turnbull's 41. Many pundits were shocked by the result, given Mr Abbott's gaffe-prone history.
A writer for the Sydney Morning Herald said that Mr Abbott's career had provided "spectacular entertainment", while ABC news' chief political writer, Annabel Crabb, described Mr Abbott's last election campaign as "a tripping, cursing, roundhouse-punch-swinging triumph of political absurdity".
As leader of the opposition, Tony Abbott's aggressive attack-dog approach earned him several nicknames.
His tactics led some to call him "Tear-down Tony" or "all opposition and no leader". He was also nicknamed the "Mad Monk" - a reference to his time spent training as a priest.
'Stop the boats'
In the 2010 general election - called after Julia Gillard ousted Kevin Rudd as prime minister - Mr Abbott's coalition denied the government a majority, as the polls delivered a hung parliament. Ms Gillard formed a government that relied on the support of a handful of independents.
The opposition leader vowed to "ferociously" hold Labor to account. "My challenge now is to ensure that I'm not the best opposition leader never to have become prime minister," he said.
As Labor infighting continued after the election, more voters swung to Mr Abbott and his party.
Ahead of the 2013 polls, Mr Abbott argued for tough border controls, lower taxes and a smaller government.
He supported Labor's policy of processing asylum seekers offshore, and went further - calling for asylum boats to be turned around and for those in Australia approved as refugees to be limited to temporary visas.
Mr Abbott has in the past dismissed climate change as faddish, but says he is not a climate sceptic.
He has promised to revoke the controversial carbon tax introduced by Ms Gillard, and replace it with a programme of subsidies for companies and farmers to reduce emissions.
He has also pledged to remove the 30% mining tax introduced by Labor, which he says drives investment overseas.
'Women problem'
Mr Abbott has consistently voted against relaxing laws on abortion, same-sex marriages and stem cell research.
In 2005, as health minister, he opposed use of the abortion drug RU486 - although this was later overturned by parliament.
However, he has since then stated he has no plans for new abortion laws, and believes that abortion should be "safe, legal and rare".
His stance on social issues, and his poor polling amongst women, has led some to say that Mr Abbott has a "women problem". In October 2012, a blistering speech by Ms Gillard in parliament accusing him of misogyny went viral online.
Days before the 2013 election, a gaffe saw him praising a female candidate for her "sex appeal".
However, many of his supporters have fiercely denied that Mr Abbott is sexist.
"Tony Abbott gets women," his wife has said. "Tony has three sisters, he has a strong, capable wife and he has been part of a team who has raised three beautiful young women."
Liberal leader Tony Abbott said he looked forward to forming a competent and trustworthy government.
Prime Minister Kevin Rudd earlier admitted defeat and said he would not stand again for the Labor leadership.
The main election issues were the economy, reducing the number of asylum seekers arriving by boat, and a tax on carbon emissions.
Mr Rudd called the election after defeating Julia Gillard in a leadership challenge in June, amid dismal polling figures that showed Labor on course for a wipe-out.
Under Mr Rudd, Labor initially saw its figures improve. But Mr Abbott, who enjoyed the strident support of Rupert Murdoch's newspapers, then widened the gap again.
"From today I declare Australia is under new management and Australia is now open for business", Mr Abbott told a cheering crowd as he delivered a victory speech.
He said that he would put the budget back into surplus, and boats bringing migrants from Asia would stop.
He added that support for Labor was at its lowest ebb for 100 years, and said the results showed that the Australia people would punish anyone who took them for granted.
Mr Rudd said he had phoned Mr Abbott and wished him well.
"I gave it my all but it was not enough for us to win," he said. But he was pleased that Labor was preserved as a "viable fighting force for the future".
Mr Rudd retained his seat in the Brisbane constituency of Griffith but said he would not re-contest the Labor party leadership because the Australian people "deserve a fresh start".
"I know that Labor hearts are heavy across the nation tonight. As your Labor leader I accept it as my responsibility," he said.
With two-thirds of the votes counted, the Australian Broadcasting Corporation said the coalition had secured 85 seats in parliament and was on course to win 91. Labor had secured 54, with a predicted final tally of 55.
In the previous parliament, Labor relied on the support of independents and the Greens for its minority government, with 71 seats to the coalition's 72.
Mr Abbott took on the leadership of the flagging Liberal-National coalition in 2009.
A Rhodes scholar who once wanted to be a Roman Catholic priest, Mr Abbott has pledged to repeal both the mining and carbon taxes introduced by Labor.
He has also promised a raft of budget cuts, including reducing the foreign aid budget by A$4.5bn ($4bn, £2.6bn).
But he says he will fund an expanded paid parental leave scheme.
Mr Abbott will be charged with managing the transition as the mining and resources boom subsides, amid slowing demand from China and slumping commodity prices.
Ahead of the polls, his coalition highlighted bitter Labor infighting, seeking to portray itself as the more stable party.
And former Labor Prime Minister Bob Hawke blamed the internal divisions for Labor's defeat.
"I really believe this was an election that was lost by the government rather than one that was won by the opposition," he said.
Julia Gillard, meanwhile, congratulated the Labor candidate who succeeded her in her seat, as she bowed out of politics.
And in something of an upset, billionaire Clive Palmer - who founded the fringe Palmer United Party - appeared on course to win a seat in parliament.
More than 14 million people were expected to vote in Saturday's election. Voting is compulsory in Australia.
Tony Abbott - Profile
When Tony Abbott took over Australia's flagging Liberal-National coalition in December 2009, his election raised a few eyebrows.
A former Rhodes Scholar who once wanted to be a monk, Mr Abbott was a polarising figure, especially at the start of his leadership.
He attracted early criticism for gaffes and was famously called a misogynist by former Labor Prime Minister Julia Gillard in a fiery parliamentary speech.
But, amid bitter Labor infighting, Mr Abbott gradually transformed his image in the eyes of many from that of pugnacious politician to leader-in-waiting.
He took on Kevin Rudd - who ousted Ms Gillard as Labor leader - in the 7 September 2013 polls and secured a convincing win to become Australia's prime minister.
'Mad monk'
Tony Abbott was born in 1957 in England to Australian parents who returned to Sydney a few years later.
After graduating in economics and law from the University of Sydney, where he was also a leading student boxer, he attended Oxford as a Rhodes Scholar, studying politics and philosophy.
He briefly trained as a Catholic priest, before working as a journalist for The Australian newspaper.
He then worked as an adviser to the Liberal Party, before entering politics in 1994 when he was elected to represent the affluent Warringah district of Sydney.
Under former Prime Minister John Howard's government, he served as an employment minister between 1998 and 2001, and as minister for health and ageing in 2003.
In 2009, he narrowly beat then leader Malcolm Turnbull in a party leadership vote, winning 42 votes to Mr Turnbull's 41. Many pundits were shocked by the result, given Mr Abbott's gaffe-prone history.
A writer for the Sydney Morning Herald said that Mr Abbott's career had provided "spectacular entertainment", while ABC news' chief political writer, Annabel Crabb, described Mr Abbott's last election campaign as "a tripping, cursing, roundhouse-punch-swinging triumph of political absurdity".
As leader of the opposition, Tony Abbott's aggressive attack-dog approach earned him several nicknames.
His tactics led some to call him "Tear-down Tony" or "all opposition and no leader". He was also nicknamed the "Mad Monk" - a reference to his time spent training as a priest.
'Stop the boats'
In the 2010 general election - called after Julia Gillard ousted Kevin Rudd as prime minister - Mr Abbott's coalition denied the government a majority, as the polls delivered a hung parliament. Ms Gillard formed a government that relied on the support of a handful of independents.
The opposition leader vowed to "ferociously" hold Labor to account. "My challenge now is to ensure that I'm not the best opposition leader never to have become prime minister," he said.
As Labor infighting continued after the election, more voters swung to Mr Abbott and his party.
Ahead of the 2013 polls, Mr Abbott argued for tough border controls, lower taxes and a smaller government.
He supported Labor's policy of processing asylum seekers offshore, and went further - calling for asylum boats to be turned around and for those in Australia approved as refugees to be limited to temporary visas.
Mr Abbott has in the past dismissed climate change as faddish, but says he is not a climate sceptic.
He has promised to revoke the controversial carbon tax introduced by Ms Gillard, and replace it with a programme of subsidies for companies and farmers to reduce emissions.
He has also pledged to remove the 30% mining tax introduced by Labor, which he says drives investment overseas.
'Women problem'
Mr Abbott has consistently voted against relaxing laws on abortion, same-sex marriages and stem cell research.
In 2005, as health minister, he opposed use of the abortion drug RU486 - although this was later overturned by parliament.
However, he has since then stated he has no plans for new abortion laws, and believes that abortion should be "safe, legal and rare".
His stance on social issues, and his poor polling amongst women, has led some to say that Mr Abbott has a "women problem". In October 2012, a blistering speech by Ms Gillard in parliament accusing him of misogyny went viral online.
Days before the 2013 election, a gaffe saw him praising a female candidate for her "sex appeal".
However, many of his supporters have fiercely denied that Mr Abbott is sexist.
"Tony Abbott gets women," his wife has said. "Tony has three sisters, he has a strong, capable wife and he has been part of a team who has raised three beautiful young women."
