What am I?

I am a portal to another world which you cannot enter. Only you can see me but I can’t see you. What am I?

related riddles

I cannot be bought, cannot be sold, even if I’m sometimes made of gold. What am I?

My life is measured in hours. I serve by being devoured. Thin, I am quick; Fat, I am slow. Wind is my foe. What am I?

I have every color, but no gold. What am I?