Jazz music is like a big musical family made up of lots of different sounds and styles. It's been around for a long time and lots of people all over the world love it. But for a long time, women weren't really allowed to join in on the musical fun. They weren't given the chance to play instruments or sing in jazz bands because people thought it was only for boys.
But over time, amazing women musicians started to make their way into the jazz scene. They practiced really hard and showed everyone that they could make great music too. Women like Billie Holiday, Ella Fitzgerald, and Nina Simone became super famous because they had amazing voices and could really sing from their hearts.
Some women also played instruments in jazz bands, like Mary Lou Williams who was an amazing piano player. They felt really proud of themselves for breaking the rules and being able to make music that people loved.
Even though it wasn't easy for women in the jazz world, they kept going and showed everyone that they could do anything they set their minds to. And now, lots of girls all over the world are following in their footsteps and becoming great jazz musicians too!