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 with HIV and Aids patients and orphans.
In 1987 she was pictured holding the hand of an Aids patient at a time when the disease was not very well understood and some people wrongly thought you could catch HIV by touching someone with it.
After her death, a special fund called the Diana, Princess of Wales Memorial Fund was set up and so far it has raised more than £100m for charities.