Corporate executives are struggling with a new trend: people using online social technologies (blogs, social networking sites, YouTube, podcasts) to discuss products and companies, write their own news, and find their own deals. This groundswell is global, it's unstoppable, it affects every industry, and it's utterly foreign to the powerful companies running things now. When consumers you've never met are rating your company's products in public forums with which you have no experience or influence, your company is vulnerable. In Groundswell, Charlene Li and Josh Bernoff of Forrester, Inc. explain how to turn this threat into an opportunity.