Simply put, word-of-mouth is the sharing of information from one person to another. Add marketing to it, and you have arguably the most credible form of promotion. While its origin is at times misconstrued as the advent of social media, it actually dates as far back as when Eve recommended Adam the apple. Typically, WOM marketing is effective, as sharing an opinion or recommendation on a product or service reflects on the sharer's reputation. That being said, Adam probably hesitated before taking Even's next few suggestions for face value.
