This document provides an overview of social media and case studies of how large brands have used social media. It discusses how social media allows for peer-to-peer sharing and interactions, and how this has changed customer behavior and expectations. Several case studies are described, such as how Dell improved customer service through social media engagement after initially refusing, and how Intuit, American Red Cross, Johnson & Johnson, and others have built communities and engaged customers online. Both successful and unsuccessful social media campaigns are examined.