Oil comes from deep underground, and it's like a special kind of liquid that has been forming for millions of years.

Long, long ago, there were tiny plants and tiny animals in the oceans. When they died, their remains fell to the ocean floor and got buried under layers of sand and mud. Over millions of years, the pressure from all the layers turned their remains into something called "fossil fuels," which includes oil.

Now, when people want to get this oil, they drill deep holes into the Earth's crust to find it. It's like using a big straw to suck up the liquid from deep underground.

The reason we call oil a "non-renewable energy source" is because it takes millions of years to make, but once we use it up, it's gone for a very, very long time. It's like eating all the cookies in the jar, and then there are no more cookies left until someone makes more cookies, which takes time.

Since it takes so long to make more oil, we have to be careful and use it wisely. We're finding and using a lot of oil faster than new oil can be made, which means it's running out more quickly than we can replace it.

That's why we try to use other energy sources, like the sun, wind, and water, which are called "renewable energy sources" because they won't run out. We want to make sure we have enough energy for the future, even when the oil is all gone.

So, oil comes from deep underground, and it takes millions of years to form. Because it's not being made as fast as we use it, we call it a "non-renewable energy source," and we need to be careful about how we use it to make sure we have enough energy for the future.