Viral growth occurs when a message is spread exponentially. Viral marketing campaigns work when a message is spread exponentially and it results in a desired outcome for a brand. Viral marketing utilises electronic means to spread messages. It harnesses the electronic connectivity of individuals to ensure marketing messages are referred from one person to another.

Viral marketing campaigns can be tricky and unpredictable. However, the lure of exponential growth, at a very low marginal cost, means that they are being attempted more often.

MSN Hotmail: from zero to 30 million

MSN Hotmail, the webmail service purchased by Microsoft, grew to 30 million members in just 2½ years from its launch in July 1996. A large part of its exponential growth is attributed to the sign-up link that was in the footer of every email sent with the service.

When the company launched, every outgoing message from this platform contained an advertisement for Hotmail and a link to its web site at the bottom of the email. As people emailed their friends and colleagues, they were also advertising the service. Recipients could simply click on the link and sign themselves up, and as they continued to email friends from their new account, the message spread within existing social networks and was passed along with little effort from the company. Hotmail went from zero to 30 million users within the first 3 years and today has over 260 million users worldwide.

There are two types of viral marketing campaigns:

· Organic or in the wild campaigns
· Amplified or controlled campaigns

Organic viral marketing
Organic or in the wild viral campaigns grow with little or no input from the marketer.
Sometimes, a message is passed around in a viral nature without any intention from the marketer. Usually this happens with negative messages about a brand, but can also be a happy coincidence for a brand if the message is positive.

Organic word of mouth is credited with the sudden increase in the popularity of Hush Puppies shoes in the mid 1990s. Word of mouth increased sales from an all time low of 30,000 in 1994, to 430,000 in 1995 and four times that the following year.

This is an example of an organic viral campaign:

· It was not planned (though it was very welcomed!) by Hush Puppies
· Participants made an active choice to pass on the message

When successful, this type of campaign can build tremendous brand equity at a marginal cost. Because the communication takes place directly between consumers, the marketer has to be prepared to let go of their brand so that the message and flow of communications is not restricted. This is vital in ensuring the viral campaign is a success as people are more likely to try a new product or fulfil the campaign goal if their friend or trusted source referred them.

Controlled viral marketing
Amplified or controlled campaigns have been strategically planned, have defined goals for the brand being marketed, and usually have a distinct method of passing on the message (that can be tracked and quantified by the marketer).

The Hotmail example above is a controlled campaign:

· The goal was to grow membership
· The emails being sent were automatically passing on the message

A viral campaign can be an important part of an eMarketing strategy. Viral marketing campaigns contribute in a number of ways:

· With correct planning, a viral campaign can providing plenty of link love for your SEO strategy. Campaigns should be built with that in mind. While there might be a microsite created for the viral campaign, ensure that it is easy to link to the main web site.

· It can be difficult to measure brand awareness, but this is usually the chief aim of any viral campaign. Bear that in mind, and make sure that the campaign is targeting the right demographic, and that branding is clear without detracting from the social nature of a viral campaign.

· Viral campaigns can also drive direct response, from newsletter sign-ups, to collaboration on consumer generated media, to purchases that can be directly correlated to the campaign.