Thanks for the query.
The answer is - Window.
Sometimes I am harder than a rock, other times I am almost weightless. Everyone wants me, but then gives me away. Some people have a lot, others have very little. I come in many different colors all over the world. What am I?
Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see. What am I?
I am spread out like a leaf. That what forms me cuts me, but builds me up. That what cuts me seeks always to go lower, but lifts its bed higher. I am commonly found where what builds me is less common. What am I?