Tap discusses how businesses can leverage consumer data from smartphones to engage in the $3 trillion mobile economy. The book explores contradictory consumer behaviors like seeking spontaneity but predictability. Drawing on case studies, it identifies nine forces that shape consumer mobile behavior, like time, location and weather. The author argues that done well, mobile advertising can act as a helpful concierge rather than stalker, and that the future opportunities of the mobile economy are vast as technologies like AI and IoT continue advancing.