What is self-sustained?

A self-sustained system is something that keeps going on its own without needing help from outside.

Imagine you have a toy car that rolls along the floor by itself, no one pushes it, no batteries power it, just whoosh! That's like a self-sustained system. It uses what it has to keep moving forever, or at least until something stops it.

Think of your toy car as having its own energy inside, maybe from wind or a little ramp. Once it starts rolling, the way the floor and the car work together lets it roll on, no need for more help.

Now think about a real-life example: a self-sustained garden. It has plants that make food for themselves, and animals that help keep the garden healthy without needing people to water it or feed them every day.

So, self-sustained means something can go on and on by itself, just like your toy car rolling along the floor, never stopping, unless something gets in its way.