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.

The classic example of viral marketing is Hotmail.com, one of the first free Web-based e-mail services. Some viral marketing strategies work better than others, and few work as well as the simple Hotmail.com strategy.

But below are the six basic elements you hope to include in your strategy. An effective viral marketing strategy:

1.Gives away products or services
2.Provides for effortless transfer to others
3.Scales easily from small to very large
4.Exploits common motivations and behaviors
5.Utilizes existing communication networks
6.Takes advantage of others' resources