Ok, so you know when you watch a ballet and there are lots of people dancing together on the stage? That's called the corps de ballet.
It's like a big group of friends who all love to dance and they get to dance together in the show. They wear pretty costumes that match each other and they do lots of fancy moves together.
The corps de ballet has an important job in the ballet. They make the show look really full and they help the main dancers tell the story with their dancing.
Even though they're not the main dancers, they still have to practice a lot and work really hard to make sure they all dance together perfectly. It's like they're all working together to create a beautiful picture for us to watch.