What am I?

I run up and down the stairs without moving. What am I?

related riddles

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?

It has a long neck, A name of a bird, Feeds on cargo of ships, It’s not alive. What am I?

what has 4 fingers and a thumb but is not living? What am I