The way businesses communicate to their stakeholders has been disrupted by the coming of Word of Mouth Marketing. Initially seen as a fad, or as a vehicle purely for teenagers and college students to communicate to each other, quite rapidly social media websites have become so essential to businesses that a high degree of adaptation has been necessary. This is not simply a change in format but a real cultural revolution. This book explores the roots of such change and how the interface Marketing-Public Relations has been affected.