For better and worse, fast food is the most pervasive culinary trend of our time. At its heart are large multinational chains, running an estimated one million outlets in virtually every corner of the world, serving hundreds of millions of customers every day. Critics have published scathing exposés, supported boycotts, engaged in demonstrations, and lobbied political leaders–usually to little effect. Why has this industry has been so successful? Why have observers been so critical? And what are the options for the future?