Social media marketing is a tactic that taps into the growth of social networks, encouraging users to adopt and pass along widgets or other content modules created by a brand, or to add a brand to the user’s social circle of friends. 
- ^ iab. IAB Interactive Advertising Wiki.
- ^ American Association of Advertising Agencies (4As). A Marketer’s Guide to Understanding the Economics of Digital Compared to Traditional Advertising and Media Services (Marketer’s Guide Series), 2009.