Can you think of the last time you saw something and you just had to tell your friends about it? Do you remember having a great experience at a restaurant and later on tweeting about it? These could be products of word of mouth marketing (WOMM). It is an organic way of spreading information. It uses components of viral marketing. Unlike viral marketing, it spreads through more natural channels.
Word of mouth is a free form of advertisement or promotion (just one reason it’s so stinkin’ important and why we love it). It’s shared by customers. As mentioned by Entrepreneur, It’s triggered by an event the customer experiences. This event is something beyond what’s expected (can be bad publicity too).