If you've never heard of viral marketing before, we won't blame you for thinking that it's the FDA's problem! This rather sinister term was coined by some very respectable people belonging to a venture capital firm called Draper Fisher Jurvetson (DFJ), who described viral marketing as a ?network-enhanced word of mouth?. Simply put, that means getting your existing clientele to act as brand ambassadors for your product. And the amazing bit is that it's quite involuntary! (Have you noticed what appears at the end of every email sent from your Yahoo account?)

Let's see how this works. Practitioners of viral marketing leverage their customer base to pass on a marketing message to others in their network. The recipients of such messages, in turn, pass the same onto their contacts, and so on. Before you know it, the message will have touched a multitude of people, pretty much like an epidemic. We see you're getting the picture?..

This is old-hat, you say. Nothing other than network marketing, a trick that's been employed by legions of marketers! True. The only difference is that this kind of marketing has succeeded beyond imagination with some internet based businesses. In fact, the good folks at DFJ invented ?viral marketing? as a tribute to Hotmail's success. Not surprisingly, the term is usually associated with internet-centric business models.

Like any other trick, not all viral marketing campaigns succeed. Certainly, only very few work as well as Hotmail does.

Why did a particular program work? It has been observed that successful campaigns had some or more of the following characteristics.

Something or the other was FREE: This never fails to work. Whether it's a free email account, or a larger mailbox or screensavers or that trial software for Arabic translation, the word FREE grabs eyeballs like no other.

It was fully transferable: Viruses love travel, and it's the same with viral marketing. A short and sweet marketing message as a tag at the end of each email, or an easy to download graphic improves chances of the epidemic raging.

It pressed the right buttons: As with any form of marketing, this too exploits an implicit need. If you're not part of an instant messaging group, you're out! If you don't blog thrice a week, you should be in a museum! At the heart of every successful campaign is its ability to create a feeling of community.

It networked, so didn't perish: And that's the crux of the whole thing. Social scientists say that each person has about a dozen people in his or her close network, and perhaps hundreds in an extended one. Viral marketing campaigns that find a way of entering communication between people have a better chance of making it. Riding on the back of someone else's success is another effective way of spreading the good word about your product. Affiliate marketing programs work on the same principle, by using traffic on popular partner websites to their advantage.

Regardless of how individual programs are structured, the hook is an implied endorsement from a friend or trusted source. The power of communication technology has helped elevate this rather simplistic proposition into almost an art form. Whether your campaign makes a pretty picture or not is another story altogether!