What are domain walls?

A domain wall is like a boundary between two different kinds of blocks in a toy castle, but instead of blocks, we’re talking about tiny particles inside materials.

Imagine you have a big box filled with colorful building blocks. Some parts of the box are all red blocks, and other parts are all blue blocks. Where the red ends and the blue begins, there’s a line, that’s like a domain wall. It's not just a line; it's where two different kinds of stuff meet up inside something very small.

Think of a playground with two sides: one side has kids playing tag, and the other side has kids playing hopscotch. The fence between them is like a domain wall, it separates what’s happening on one side from what’s happening on the other. Even though both sides are part of the same big playground, they’re doing different things.

Sometimes, when something changes inside the material, like when you cool it down or warm it up, these domain walls can move around, just like kids might move the fence to make a bigger area for their game.