The 31st of August marks 20 years since the death of Diana, Princess of Wales, the mother of Prince William and Prince Harry.
Diana was one of the most famous people in the world and she was really popular with many people in the UK.
Her death in a car crash shocked the country at the time, and it is still talked about today.
Here Newsround looks back at her life.
Diana was born on July 1, 1961. She had two older sisters and a brother.
Her family was wealthy and had been close to the Royal family for generations.
Diana's parents split up when she was very young and later divorced.
Diana went to boarding school and although she didn't do very well, she always said her time there was a happy one.
After school, she worked as a nanny in London, and then became a nursery assistant.
Diana's life would change forever when she married Prince Charles.
The two met in the 1970s and he proposed to her in 1981.
They were married in St Paul's Cathedral watched by 3,500 invited guests and an estimated 750 million people around the world on live television.
Soon after the wedding, Diana became involved in the official duties of being a princess and visited lots of schools and hospitals.
Diana became a big favourite of the public very quickly. Lots of people felt that she seemed really happy to speak to normal people and talk to them about their lives.
Prince William was born on June 21, 1982, followed two years later by Prince Harry.
The princess wanted her children to have as normal a life as possible, for members of the Royal Family.
During her life, Diana did a lot of work to raise money for charity.
She was famously photographed walking across a minefield in Angola as part of a campaign to end the use of landmines.
The princess also did lots of work to raise awareness of HIV and Aids, often visiting patients and orphans.
Diana's life changed again when she and Charles separated in 1992 and were divorced in 1996.
Diana said life was difficult for her after the break-up. She was still really popular with the public though, and lots of newspapers called her the 'People's Princess' after her divorce from Charles.
All this attention meant she was constantly being followed and photographed by the press who knew papers with stories about Diana in them would sell very well.
In 1997 Diana visited Paris. It was there that a car she was travelling in crashed in a tunnel while being followed by photographers in cars and on mopeds.
Lots of people were really shocked and saddened by her death. Millions of people gathered and left flowers, cards, candles and messages at Kensington Palace, where she had lived.
The Queen paid tribute to Diana in a speech on TV, but the Royal Family were at Balmoral Castle in Scotland when Diana died, and were criticised by some for not coming to London sooner.
Diana's funeral was broadcast on TV and was a huge event - thousands of people lined the streets as her coffin went by.
Diana was buried on an island on the Spencer family estate, Althorp.
In 2000, a Diana Memorial Children's Playground was opened next to her Kensington Palace home and in 2004 the Diana Memorial Fountain was opened in Hyde Park in London, in her memory.
A special fund called the Diana, Princess of Wales Memorial Fund was set up and so far it has raised more than £100 million for charities.
To mark the anniversary of her death, Princes William and Harry have organised for a statue to be built in the gardens of Kensington Palace.
They have also been talking about their memories of their mother on television.