Viral Marketing

viral marketing Accoring to Dr. Ralph F. Wilson:

Viral marketing describes any strategy that encourages individuals to pass on a marketing message to others, creating the potential for exponential growth in the message’s exposure and influence. Like viruses, such strategies take advantage of rapid multiplication to explode the message to thousands, to millions.

According to Wikipedia:
Viral marketing and viral advertising refer to marketing techniques that use pre-existing social networks to produce increases in brand awareness, through self-replicating viral processes, analogous to the spread of pathological and computer viruses.

It can be word-of-mouth delivered or enhanced by the network effects of the Internet.  Viral marketing is a marketing phenomenon that facilitates and encourages people to pass along a marketing message voluntarily. Viral promotions may take the form of funny video clips, interactive Flash games, advergames, images, or even SMS text messages.