I am 16 years old and want to begin with photography. I have budget of around 200 euros, with a maximum of 250 euros. I want to make some shots of the sky or of nature, so a good optical zoom would be helpful. I don't really know what to buy.
It depends how "far" you want to go on photography, for now. If you want just to start and get to know what photography is, I recommend you a Bridge. It gives you plenty of things to learn. If you just want to take snapshots on trips, go for a Compact.
If you intend to get heavily involved in photography, and spend more money later, then for that price range, I would probably recommend buying a used DSLR with a kit zoom lens.
This will be enough to begin learning, and find where you feel limited. When you feel limited, that is the time to upgrade. I would suggest your next upgrade would be a new lens or two... and then eventually you can upgrade your camera body, and continue using your new lenses.