This book examines principles and applications of social media in interpersonal, mass-mediated, educational, organizational, and political settings. Social media technologies take on many different forms, including social network sites like Facebook and Twitter, blogs, wikis, online video and photo-sharing sites (e.g., Pinterest), rating and social bookmarking sites, and video/text chatting sites (e.g., Skype). The first three chapters of the book focus on the principles of social media. Other six chapters cover applications of social media in a variety of settings. Overall, this book answers some of the following questions: Who uses social media? Can we develop meaningful relationships through social media? How do people use social media during natural disasters and crises? How do people use social media to get social support and evoke political change? Is privacy dead? How do employers use social media to check on employees? How do teachers and students communicate using social media? How do advertisers use social media to promote their products and services? Why are people addicted to social media?