Ghose's book "Tap" discusses how businesses can tap into consumer data from smartphones to understand behavior and harness the $3 trillion mobile economy. It explores how consumers act predictably yet seek spontaneity, and value privacy but use personal data as currency. Ghose identifies nine forces that shape consumer behavior like time, location and weather, and how mobile technology can influence shopping if advertising respects consumer preferences over stalking. The book welcomes readers to a growing mobile economy with opportunities in an advancing technological landscape.