WOM vs Viral Marketing

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Word of mouth marketing is a vital tool to any marketing endeavor. And these days social media and viral marketing are becoming important tools as well. But what is the difference between WOM and social media? Will a twit or viral youtube vid create a sale? No neccessarily, so what is it's role and how can you keep your demographic focused on the content rather than the medium? How can you generate WOM advertsing for an event when you are using mainly viral marketing? Any points or suggestions you may have are helpful. Thanks for the help guys :)