The document discusses the rise of social media and its implications for marketing. It notes that Web 2.0 enabled a shift to "many-to-many" communication as opposed to the "one-to-many" model of traditional media. Various social media platforms are described including social networks, blogs, microblogs, video/photo sharing sites, and geolocation services. The large audiences on sites like Facebook, Twitter and YouTube are cited. Integrated marketing strategies using different social media channels are recommended. Challenges for marketers like niche audiences and vocal online critics are also outlined.