Answer:
When I am caught I am thrown away. When I escape you itch all day.
I run up and down the stairs without moving
I am a ship that can be made to ride the greatest waves. I am not built by objects but built by minds.
When you stop and look, you can always see me. If you try to touch, you cannot feel me. I cannot move, but as you near me, I will move away from you. What am I?
When you take away the whole from me, there is always some left. What am I?
No matter how little or how much you use me, you change me every month.