D-brane

Alright, imagine you have a big empty room that represents the universe. Now imagine you throw a ball into the room. The ball moves around and can bounce off walls and other things in the room, right?

Now imagine the ball is actually a super tiny string, and the room is actually a ten dimensional space that we can't see or feel, but it's there.

But here's the catch: this tiny string ball can only move around on a specific flat surface that's called a "brane" (short for membrane). Think of it like a flat sheet of paper that's stretched out in the universe. This brane is known as a "D-brane".

So while the string ball is staying on the D-brane, it can still bounce around and move like before. But if it tries to move off the D-brane, it just disappears into the other dimensions and we can't see or interact with it anymore.

D-branes are really important in a theory of physics called string theory. Scientists use them to explain how tiny strings move around in the ten dimensional universe.