Dear little one, have you ever played with a piece of string? Imagine you have a really long string and you tie one end of it to something, maybe a chair or a table. Now, you stretch the rest of the string out as far as you can until it's tight.
Next, you take your other hand and you grab onto the string somewhere in the middle. You don't let go of it, but you also don't pull it really hard or anything. You just hold onto it gently.
Now, imagine that this middle part of the string is like a little world all on its own. Just like how we live in the big world, the middle of the string has its own little world too.
The homotopy fiber is a fancy way of talking about this middle part of the string. It's the part between where you tied the string to the chair and where you're holding onto it in the middle.
But why do we care about this middle part?
Well, sometimes we use the homotopy fiber to help us understand other things. When we study math or science, we often need to compare different things or look at them in different ways. The homotopy fiber is one of those ways that we can see things differently and maybe learn something new.
So next time you play with a piece of string, you can imagine that you're exploring your very own little world in the middle of it!