My 15 yo son rides his bike pretty hard so the odd breakage is inevitable.
He has snapped, what I believe is called, the derailleur hanger.
We'll need take it to the shop to get fixed as it appears to need some specialist tools to remove and re-install.
I'm keen to hear from someone who knows about this sort of stuff please, to give me an idea of how much I can expect to pay for this repair.
(The bike is a GT Aggressor, if that's relevant at all.)