Universal bundle

A universal bundle is sort of like a bag that contains lots of smaller bags, and each of these smaller bags holds something different. But instead of bags, the universal bundle is made up of spaces, and instead of holding things, these spaces hold mathematical things called "fibers."

Sometimes we want to look at a big space and see what smaller spaces are inside of it. This is where the universal bundle comes in handy. It's a way of "packing up" all the smaller spaces together in a neat and organized way.

For example, imagine a big space that represents all the directions you can move in--up, down, left, and right. We can use the universal bundle idea to "pack up" all the directions at each point in this space into a neat little package. This package would contain four smaller spaces, one for each possible direction.

Overall, the universal bundle helps us understand how different spaces come together and how they relate to one another. It's like a big, organized toolbox full of smaller tools that we can use to better understand the world around us.