DEFINITION of 'Viral Marketing'
Internet advertising or marketing that spreads exponentially whenever a new user is added. Viral marketing assumes that as each new user starts using the service or product, the advertising will go to everyone with whom that user interacts.
BREAKING DOWN 'Viral Marketing'
An example of viral marketing is Hotmail, which offers free web-based email. Each time a user emails someone, there is an embedded advertisement to the recipient to sign up for a Hotmail account. While the practice was much more widely used in the early to mid-2000s as new internet businesses were being created in extreme numbers, it is still common among internet based business-to-consumer (B to C) companies.