Most people sign on to one or more social media accounts every day without giving much thought to how these services are offered for free. This timely volume explains to readers how social media sites use their personal data to make a profit. By explaining how advertising targets specific demographic groups and how big data firms make use of individuals’ information, this book gives readers a clear understanding of their place in the social media business model. In addition, readers will learn how they can take steps to protect their privacy and reduce the amount of information available to data mining companies. Illustrations and in-depth sidebars round out the text.