King Charles III will be officially crowned during his coronation ceremony in London on Saturday, May 6, but what can the world expect from his reign?
After being the longest monarch in waiting, King Charles will have the chance to put his stamp on the centuries-old institution as head of the Royal Family and the Commonwealth.
And in Australia his reign is expected to reignite the debate over whether the country becomes a republic.
The life of King Charles III in pictures
We spoke with historian Benjamin Jones, of Central Queensland University, about the significance of the royal coronation at Westminster Abbey and what to expect from the reign of King Charles III.
Is he King of Australia?
Charles is the Australian head of state in his own right, under a constitutional arrangement separate from his role in Britain.
In Australia, the monarch is represented by the governor-general, under the country's constitution.
While the King rules "without political power", the monarch wields "power with influence", Jones said.
Rather than a combined type of monarchy, under separate relationships, he is the individual monarch of the Commonwealth nations, separate to the British monarchy.
So when he visits Australia, he is the King of Australia.
How important is the coronation?
Jones said it's highly significant for the King and for Australians because it will be the first coronation since that of Queen Elizabeth II in 1953.
"The coronation is an opportunity to set the tone for his reign ... and it comes when many of his subjects, in Britain and throughout the Commonwealth nations are experiencing a cost of living crisis."
Organisers have emphasised the ceremonies and celebrations will be about inclusion and sustainability, reflecting the mood of the times.
The wife of King Charles III, Queen Camilla, will wear Queen Mary's Crown during the ceremony.
It will be the first time in recent history that a consort has opted to reuse an existing crown rather than commission a new one to be made.
Buckingham Palace said Camilla's choice was "in the interests of sustainability and efficiency".
Jones said King Charles III is eager to tone down the lavishness of the coronation, with a reduced VIP guest list and an emphasis on community events.
"The monarchy exists with one eye constantly on public opinion ... so Charles knows an overly lavish ceremony will not play well with the public."
Will Australia become a republic during his reign?
When it came to power last year, the Albanese government signalled it was taking steps towards a republic, meaning the end of the monarchy in Australia.
Prime Minister Anthony Albanese appointed Matt Thistlewaite as the assistant minister for the Republic of Australia.
But domestic politics mean a referendum on the republic will not be held during this federal parliament.
Currently the government's top priority is building public support for a referendum on the Indigenous Voice to parliament, expected to be held later this year.
It means a vote for a republic won't happen until after the 2025 election at least. And even that depends on the party that takes power.
King Charles III before he became monarch insisted it was up to Australia to decide whether it wanted become a republic.
"Has no deep burning desire to weld Australia to monarchy forever," Jones said.
The King will also be sensitive to republican support in other Commonwealth countries.
They are more likely to move quicker than Australia to scrapping the monarchy because of the crown's association with slavery.
"The last thing Charles will want is to trigger a domino effect of countries leaving the Commonwealth ... it would be nightmare for his legacy," Jones said.
King Charles III has said Australia should decide its own constitutional arrangements. (Sam Ruttyn/Pool via AP)
Will King Charles III push for more climate action?
The monarch has been a fierce defender of the environment and has been calling for action to combat climate change for decades.
In a speech at the COP26 Summit in Glasgow in November 2021, the then Prince Charles implored countries to work with industries to create solutions to climate change.
"We know this will take trillions, not billions, of dollars," he said. Climate change and loss of biodiversity pose a great threat and the world must go on a "war-like footing" to combat them, he added.
But King Charles III will have to temper his passion for climate change and other social issues in the years ahead to maintain the crown's political neutrality, Jones said.
Instead he will try to emulate the political neutrality of Queen Elizabeth II.
"As a prince he was more vocal on political issues ... but as King he will follow his mother who left politics to the politicians."
Kate congratulates England team in changing room
