The Prince of Wales is to marry Camilla Parker Bowles in a civil ceremony on 8 April.
The wedding of the future monarch has prompted a series of questions.
New rules mean the prince could marry Mrs Parker Bowles in church
Have both Charles and Camilla been married before?
The marriage of Prince Charles to Diana Spencer in 1981 was broadcast around the world. Their separation in 1992 and divorce in 1996 also prompted huge interest.
Less well known is Mrs Parker Bowles' marriage to Andrew Parker Bowles, a former Silver Stick-in-Waiting to the Queen, in 1973. The pair divorced in 1995.
How long has their relationship been going on?
They first met in 1970 and dated for a time, but after the prince decided to concentrate on a naval career Camilla married.
Their relationship was rekindled in 1986, with Princess Diana later complaining there were "three in the marriage".
It was only after Diana's death in 1997 that their relationship became more widely accepted. They first appeared together for the cameras in 1999.
Where will they marry?
Prince Charles' first marriage was held in St Paul's Cathedral with huge crowds and worldwide coverage.
This time he is opting for a more private venue, Windsor Guildhall.
It will be a private civil ceremony but the Archbishop of Canterbury will then preside over a 45-minute service of prayer and dedication in the Windsor Castle's St George's Chapel. The blessing will be attended by about 750 guests and televised live.
What is the Church of England's position?
The Church is divided and had been seen as the biggest obstacle to Prince Charles remarrying, not least because he would be Supreme Governor of the Church of England if he becomes King.
Some groups are opposed to divorce, and to divorcees remarrying, but former Archbishop of Canterbury Lord Carey has previously said he hopes Prince Charles will "take the plunge" as a way of regularising their relationship.
Why are they not marrying in church?
It is not known whether the couple would have preferred a church wedding. The Church has scrapped its ban on divorcees marrying in church if their former spouses are still alive.
It says priests should consider whether the couple's relationship caused the previous marriage's breakdown. Archbishop of Canterbury Rowan Williams welcomed the wedding, saying the arrangements were in line with Church guidelines.
Did anybody need to give permission for the marriage?
Yes, the Queen. The Royal Marriages Act of 1772 means the monarch can ban any of their relatives from getting married. She would have consulted the prime minister, who in turn would have talked to the Cabinet and Opposition.
Prince Charles could have by-passed the Queen, but Parliament could have then overruled his decision.
Will Camilla ever be called Queen?
She would be entitled to be known as Queen Camilla if Charles became King because, under law, she would automatically inherit that title.
Charles had previously announced that Camilla would be known as Princess Consort, not Queen. She will also be called Her Royal Highness the Duchess of Cornwall. Legally, she will be the Princess of Wales, but will not use the title.
But Thurrock MP Andrew McKinlay said "Prince Charles has been less than frank with the country", because new legislation would be needed to stop Camilla having the rights of a Queen.
Given the Queen's rude health, it could be that the law would not need to change for many years anyway. With Charles as King, Parliament could decide to enshrine in legislation the couple's wish for Camilla to be known as Princess Consort.
Charles' advisors say convention and not law dictate who is known as Queen. There may also be no action if the majority of the population had come to accept the idea of a Queen Camilla.
Does the marriage affect the succession to the throne?
No. Prince Charles remains heir to the throne, with his and Princess Diana's oldest son, Prince William, next in line to the throne. Any change in the succession needs the assent of all Commonwealth members.
Mrs Parker-Bowles has two children, Tom and Laura, from her first marriage but they do not join the line of succession.
What do the public think?
Recent opinion polls suggest that people are divided about the idea. A Populus poll for the Sun newspaper suggested 40% would approve of a marriage, 36% were against and 24% had no opinion. An earlier poll in July suggested the public opposed Camilla becoming Queen by a three-to-one margin (21% in favour, 74% against).