Fingers and thumbs turn design conventions on their head. Touchscreen interfaces create ergonomic, contextual, and even emotional demands that are unfamiliar to desktop designers. Find out why our beloved desktop windows, buttons, and widgets are weak replacements for manipulating content directly, and learn practical principles for designing mobile interfaces that are both more fun and more intuitive. Along the way, discover why buttons are a hack, how to develop your gesture vocabulary, and why toys and toddlers provide eye-opening lessons in this new style of design.