Democrats are celebrating. In Canberra, Ritu Clementi and her son, Nikhil, from Democrats Abroad see a new era dawning.
"We have been living for four years of Trump ignoring our basic Constitution and decency. We are now turning towards a time of a united America," she said outside the American embassy. "For once, we are moving towards unity," he said.
So what can they and other Americans expect?
Mr Biden and his chief of staff, Ron Klain, have given strong indications.
The immediate task
The Day One priority will be addressing the epidemic, with measures to improve health and to keep the economy from toppling over, including pushing for $2.6 trillion in spending.
He is expected to make wearing masks compulsory on government property and on travel between states.
He has said he wants to ensure that 100 million doses of vaccine have been given before the end of his first 100 days.
He wants to change the war time Defense Production Act so that the government can compel companies to prioritise manufacturing vaccines.
He is also expected to announce that the United States will rejoin the World Health Organisation from which Mr Trump pulled out.
What else on Day One?
Mr Klain, who was Mr Biden's chief of staff when he was vice president, told the US media that the new President would promptly undo some Trump decisions.
Mr Biden would recommit to the global agreement on tackling climate change, known as the Paris Accord.
Mr Biden would also end the so-called "Muslim ban" on travel from a string of countries, including Syria, Iran, Iraq, Sudan, Libya and Yemen.
He has said he would send a bill to Congress "for legislative immigration reform that will modernise our immigration system and give nearly 11 million undocumented immigrants a roadmap to citizenship".
He would repeal a ban on transgender people serving in the military.
The first 100 days
Mr Biden will need Congress to approve some of the measures he wants. That will be easier because there is now a Democrat majority in both houses, but it's wafer-thin in the Senate so he has his work cut out.
He wants to repeal Mr Trump's tax cuts which he and other Democrats argue favoured the very wealthiest Americans.
Mr Biden has said he would tighten gun law and make it possible for relatives of victims of gun violence to sue gun manufacturers.
Beyond the early days, the new president comes to the big and complex issues which are not soluble at a stroke. They demand policy.
Top of the list is how to deal with China as its power rises and it gets more assertive.
President Trump put tariffs on hundreds of billions of dollars of products from China. He imposed sanctions on Chinese companies and blocked Chinese businesses from buying American technology.
Mr Biden will have to decide whether to stick with that confrontational approach or to negotiate a reduction in tariffs. Negotiations require some give as well as take.
According to the American media, Mr Biden will walk a fine line, trying to work with China on some issues, particularly on environmental measures, while being tough on other issues such as Chinese military expansionism, human rights violations and "unfair" trade.
The big question (of great interest to Australia) is: how would the US deal with aggressive expansion in the South China Sea or in Taiwan?
What would America do if push comes to shove?
And what will it expect Australia to do?
Mr Trump made a big show of meeting North Korean despot Kim Jong-un. There was an amazing photo opportunity where the two greeted each other at the Demilitarized Zone which divides North and South Korea.
The American president appeared to believe that his deal-making abilities and a personal chemistry would solve the problem of North Korea's nuclear-armed missiles capable of hitting both Washington and Australia.
Despite the performance, Mr Kim's missile development continued.
Mr Biden's choice is between tougher sanctions and some attempt to engage, perhaps promising a lot of money to North Korea to disarm.
Experts do not hold out much hope with either strategy. Mr Kim seems set on nuclear weapons.
Despite Mr Trump's assertions (and the assertions of his Ambassador in Canberra), the relationship with Australia was not as clear as it had been.
Mr Biden may well assure allies such as Australia that the alliance is rock solid.