Margaret Sanger was a lady who lived a long time ago, like over 100 years ago! She was really passionate about making sure women had control over their own bodies and could make their own choices about having babies or not.
Back then, not a lot of people had very good information about how to prevent babies from being born. This sometimes led to situations where women had way more babies than they wanted or could take care of. Margaret Sanger thought this wasn't fair to women and families, so she started telling people about ways to prevent pregnancies.
She talked to lots of people about these ways and even started a magazine to share her ideas. Some people didn't like what she was saying though, and they thought that it was bad to talk about how to not have babies. Margaret didn't give up though- she even went to jail for a little while!
In the end, Margaret helped start a group that still exists today and is called Planned Parenthood. They work really hard to give people information about how to prevent pregnancies and stay healthy. Margaret Sanger is remembered as someone who stood up for what she believed in and tried to make the world a better place for women.