Is this damp or mold?

[fakenamefornow]

And what should we do about it?

It's on the join between sloped ceiling and wall.

My guess is mould as it is spotty.

Is it where the condensation hits the wall?

What's on the other side of the wall/ceiling - exterior/roof?

Looks like mould to me, get some mould remover and give it a good clean, are the windows opened much in that room?

Thank you!
I thought mould.
It's an external roof/wall.
The windows are open a bit and the room is heated. It's my teenage daughter's bedroom and she spends an awful lot of time in there. I've told her to open the window more and make sure she has her radiator on in the winter.

We get the same in one bedroom in winter. It eventually spreads but clears up in summer. We scrub it off once a year but a more permanent solution would be good.

Did you bump this thread just to advertise your business?

I've reported it, may be a bot

Not even subtle. 1/10. Try harder.