You stick your poles inside me. You tie me down to get me up. I get wet before you do. What am I?

I come in many shapes, with buttons and screens, I help you create, and fulfill your dreams. Though I may seem simple, I hold great power, What am I, that you use every hour?

Across and down my clues are pressed; Small squares wait while minds are tested. Words all meet where letters are shared.

When the metal is soft and hot It's held to my face but fear not There's no pain that I feel For I'm made out of steel So hammer me with your best shot

I hide in strings and wooden keys, I flutter out on laughing breeze. I make your shoulders sway and swing, without a single visible thing.