Feels like you're floating on air. Because you are.
The TPad is a variable-friction tactile display. It changes friction, or resistance force, as you slide your finger across the screen. When it's on, your finger feels light and is easy to move. Beneath your finger, the surface is moving up and down less than the width of a strand of spider silk at frequencies faster than humans can hear. Your skin bounces against the surface, and is supported by a film of air like an air hockey table. It's literally floating on air.