Liquid nitrogen

Okay little buddy, do you know what nitrogen is? It's a gas that's in the air we breathe. It's invisible, so we can't see it.

Now, imagine we take that gas and make it super duper cold, like really really cold. When we do that, it turns into a liquid and that's what we call liquid nitrogen.

It's called liquid because it looks like water, but it's not water. It's so cold that if you put your hand in it, it would freeze! That's why we have to be very careful when we use it.

People use liquid nitrogen for lots of things like freezing food or making ice cream really really fast. Scientists and doctors also use it for fun experiments and to treat certain medical conditions.

But remember, liquid nitrogen is something that only grown-ups should use because it can be really dangerous if we're not careful with it.

So that's what liquid nitrogen is, a super-duper-cold liquid that we need to be really careful with. Cool, huh?