Well, you know how sometimes when you watch a movie or a read a book, it's not just one story, but three stories that are all connected? That's called a trilogy!
Imagine you have a favorite toy, let's say a doll. And you love playing with it so much that you want to make up lots of different stories with it. So, you decide to make up three different stories that all involve your doll.
In the first story, your doll goes on an adventure to find a special treasure. In the second story, your doll has to save her friends from a big monster. And in the third story, your doll meets a new friend and they go on a trip together.
The cool thing about a trilogy is that all three stories are related to each other. Maybe some of the characters from the first story come back in the second and third stories, or maybe there's an important object that shows up in all three stories.
When you watch or read a trilogy, you get to see how everything connects and how the characters grow and change throughout each story. It's like a big, exciting puzzle that you get to put together in your head!