What's under my stairs carpet please?

[Ihavenobrain]

I live in a fairly new house. It's about 20-25 years old.
What would be under my carpet?
And could it be painted?

You'll have to lift it to check. Likely to either be floorboards or possibly mdf treads, but don't take my word for it as I have no way of knowing!

I agree. It's probably just floorboards. But you will find out once you lift the carpet. If it's just floorboards then painting them wouldn't look good.

Downstairs, quite probably concrete.
Concrete, smoothed, painted and polished, can look fab but it's bloody cold - great in the tropics, less so in Blighty.