Baroness Thatcher, who died this week aged 87, was Britain's first, and so far only, female leader.
At the time of her election as PM in 1979 politics was dominated by men - only 3% of MPs were female. So, when she became prime minister in 1979 very few women were debating the big issues that affected the country.
Today, almost a quarter of MPs are women.
US President Barack Obama described her as a role-model for women - saying "She stands as an example to our daughters".
But not everyone thinks Lady Thatcher was a champion of female achievement.
Margaret Thatcher liked to be surrounded by men in her work and didn't think women should get special treatment, just so they could catch up with men in top jobs.
While her politics divided opinion, her role as Britain's first female prime minister will forever go down in history.