Back-story in a production is like the story that explains why the characters in a play, movie, or TV show act the way they do. Imagine you are playing make-believe with your friends, and you decide to pretend you are a superhero. If someone asks you why you are wearing a cape, you might say, "Oh, I wear this cape to fly and fight bad guys." That's like the back-story of your superhero character.
In a production, the back-story usually involves writing and creating details about the characters' past experiences, relationships, and beliefs. This helps the actors understand their characters better and gives them ideas for how to act and speak. For example, if a character in a TV show always wears a certain necklace, the back-story might explain that the necklace belonged to her grandmother, who was a famous artist. This would help the actor understand why the character values the necklace so much and how it might affect her behavior.
The back-story can also help the writers come up with new ideas for the story. For example, if the back-story reveals that a character has a fear of heights, the writers might create a scene where the character has to climb a tall building. This adds more depth and drama to the story.
Overall, the back-story is like a secret diary for the characters in a production. It helps everyone understand the characters better and adds more depth to the story.