Evangelism is word-of-mouth marketing. It’s the best kind of marketing because it’s honest and personal. We don’t pay attention to television commercials and magazine ads because we don’t trust them. We do, however, trust our friends recommending something to us.
And so, companies want their customers to tell their friends about the product. But try as you may, you can’t force people to talk about your product, which means that the next best thing is to try and get people to at least use it.
Shawn Blanc — You Can’t Buy Word of Mouth.