Silicon on insulator or SOI is like a sandwich with three layers - the first layer is silicon, the second layer is an insulating material, and the third layer is also made of silicon. It is used in electronics to make computer chips that are faster and better.
The insulating layer in the middle can be made of different materials such as glass or a special type of silicon oxide, which helps to keep the electrons (tiny particles that carry information) inside the top layer of silicon. This means that the electron movements are better controlled and the computer chip can be faster and more efficient.
Think of it like this - when you play with blocks, you can build a tower that will stand tall and strong if you have enough blocks and stack them carefully. Imagine each block is a tiny piece of a computer chip, and the SOI sandwich is like an extra-strong foundation for the blocks to sit on. This helps the computer chip to work better and faster than if it was just made out of silicon alone.